Patent Publication Number: US-2023152053-A1

Title: Gun barrel assembly

Description:
The present invention relates to a gun barrel assembly. 
     More particularly, the present invention relates to a smoothbore barrel for long-barreled firearms designed to shoot shotshells. 
     Numerous and varied configurations of the barrel, designed to improve the performance of the firearm from a technical standpoint, are known. 
     The desirable features are numerous and often conflicting. 
     For example, a desirable feature is a higher shot speed at any distance comprised between the muzzle and the range, which would offer the advantage of reducing anticipation and of aiming directly at the target. 
     Another desirable feature is greater penetration energy, which offers the advantage of increasing the arresting power. 
     A further desirable feature is a longer range, which offers the advantage of increasing the useful firing distance. 
     Another desirable feature is an optimal ballistic performance regardless of the ammunition used. 
     A further desirable feature is to have no constraints on the type of choke with respect to the cartridges that can be used. 
     A further desirable feature is to reduce manufacturing limitations, due to the relationship between the material and the choke ratio, currently found in standard barrels. 
     Another desirable feature is the possibility of reducing the pressure variation at barrel exit, with the advantage of reducing noise on firing. 
     A further desirable feature is a reduced recoiling force. 
     Some of the above features have been obtained, in a limited way, by prior art barrel assemblies. 
     For example, Italian Patent IT1405143 discloses a barrel assembly with a constant bore diameter of various sizes:
     a bore diameter D1 corresponds to a unified gauge (standard conical portion between chamber and bore);   a bore diameter D1′ that is out of gauge, with D1′ = D1 + 0.3 mm (reduced conical portion between chamber and bore);   a bore diameter D1″ that is out of gauge (e.g., from 20.3 mm for 12-gauge), and in particular is equal to the minimum diameter of the cartridge chamber 2 (no conical portion between chamber and bore);   an expansion chamber D4 between the bore and the barrel muzzle with a diameter of + 0.3/1 mm, beyond the bore diameter.   

     US5155291A discloses a barrel that allows a prior opening of the shot pattern by means of a divergent segment in the end part. 
     The web page https://www.mossberg.com/category/series/835-ulti-mag/ describes a 12-gauge barrel with a 10-gauge bore which would allow for uniform shot patterns, but with no mention of speed. 
     US6289620B1 discloses the use of multiple conical portions to minimize recoiling force, without altering shot exit speed. The document explains that 18.4 mm bore diameters ensure speed and arresting power, while 18.8-18.9 mm diameters are said to ensure less recoiling force but also a lower bullet exit speed. Multiple conical portions should combine the advantages of both solutions. 
     The web page https://www.beretta.com/en/691/ describes barrel assemblies that should ensure higher shot pattern density with high penetration, a smaller muzzle rise and, finally, a fast and accurate second shot. 
     DE102014014401A1 discloses a rifled barrel having an entry region which merges into a front barrel part ending in a muzzle region; the region between the entry region and the muzzle region forms an acceleration channel which has a diameter which is enlarged in relation to the diameters of the entry region and the muzzle region. 
     US11022394B1 discloses a multi-bore rifled barrel having a proximal chamber end, a distal muzzle end, and an internal bore bounded by a bore wall where the internal bore has a cartridge chamber at the proximal chamber end of the barrel, a first rifled bore section distal to the cartridge chamber, a second rifled bore section at the distal muzzle end of the barrel, and a reducing section distal to the first rifled bore section and connecting the first rifled bore section and the second rifled bore section. 
     US4058925 discloses a pattern control system for a shotgun in which choke attachments are detachably mounted on the muzzle end of the shotgun barrel and the barrel bore and progressively reduced choke constrictions, either in the bore and the choke attachments or in the attachments alone, are formed at the same time in order to eliminate tolerance buildup between the choke attachment bore constrictions and the barrel bore. 
     Each of the above mentioned systems, however, offers only a limited number of desirable features; none of the prior art barrels is capable of combining all the features into a single assembly. 
     The aim of the present invention is to provide a new gun barrel assembly that overcomes the drawbacks of the cited prior art. 
     Within the scope of this aim, an object of the invention is to provide a gun barrel assembly that allows to obtain a higher shot speed at any distance comprised between the muzzle and the range, offering the advantage of reducing anticipation and of aiming directly at the target. 
     An object of the invention is to provide a gun barrel assembly that allows to have a higher penetration energy, with the advantage of increasing the arresting power. 
     A further object of the invention is to provide a gun barrel assembly that allows to have a greater range and thus increase the useful firing distance. 
     A further object of the invention is to provide a gun barrel assembly that offers optimal ballistic performance with any ammunition. 
     A further object of the invention is to provide a gun barrel assembly that offers the possibility to have no constraints on the type of choke, with respect to the cartridges that can be used, and to reduce manufacturing limitations due to the relationship between the material and the choke ratio. 
     A further object of the invention is to provide a gun barrel assembly that reduces the pressure variation at barrel exit, with the advantage of reducing noise on firing. 
     A further object of the invention is to provide a gun barrel assembly that reduces the recoiling force. 
     A further object of the invention is to provide the user with a barrel assembly with a length that is variable depending on the type of sports or hunting use. 
     A further object of the invention is to reduce the production, management and purchase costs of barrels. 
     A further object of the present invention is to provide an assembly which by virtue of its particular constructive characteristics is capable of giving the greatest assurances of reliability and safety in use. 
     This aim, these objects and others which will become better apparent hereinafter are achieved by a gun barrel assembly, as claimed in the accompanying claims. 
    
    
     
       Further characteristics and advantages will become better apparent from the description of preferred but not exclusive embodiments of the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein: 
         FIG.  1    is a schematic sectional view of the barrel according to the present invention; 
         FIG.  2    is a schematic view of an example of the proportional dimensions of a barrel according to the invention configured with a divergent-convergent profile; 
         FIG.  3    is a schematic view of an example of the proportional dimensions of a barrel according to the invention configured with a convergent profile; 
         FIG.  4    is a schematic view of an example of the proportional dimensions of a barrel according to the invention configured with a divergent profile; 
         FIGS.  5  and  6    are schematic views of test methods and of the results obtained with the barrel according to the present invention compared with traditional systems; 
         FIG.  7    is an exploded view of an embodiment of the barrel, constituted by three components; 
         FIG.  8    is a sectional view of a barrel provided with a configuration having an inner choke member; 
         FIG.  9    is a sectional view of a barrel provided with a configuration having an extension and an inner choke member; 
         FIG.  10    is a sectional view of a barrel provided with a configuration having an inner choke member; 
         FIG.  11    is a sectional view of a barrel provided with a configuration having an extension and an outer choke member; 
         FIG.  12    is a partial sectional view of a double barrel provided with a 3.5” powder chamber; 
         FIG.  13    is a partial sectional view of a double barrel provided with a 3″ powder chamber; 
         FIG.  14    is a partial sectional view of a double barrel provided with a 2¾″ powder chamber. 
     
    
    
     With reference to the cited figures, the gun barrel assembly according to the invention, generally designated by the reference numeral  1 , has a first segment, designated by the reference numeral  3 , which is extended after a chamber  2 , and has a divergent-convergent configuration, constituted by a divergent portion  31  and by a convergent portion  32 , or with a solely convergent or solely divergent configuration. 
       FIG.  1    shows an embodiment having the configuration with a divergent portion  31  and a convergent portion  32 . 
     The barrel  1  includes a bore  4 , followed by a segment having an increased diameter  5 , which may have a constant configuration, as in  FIG.  1   , or a divergent configuration, and an end choke constituted by a first end portion  6  and a second end portion  7 . 
     The profile of the barrel according to the present invention is defined by means of a mathematical formula that describes the optimized internal profile along the entire length of the barrel, from the chamber  2  to the muzzle  8 , and contains only the chamber length and diameters defined by the CIP standard (D, H and L) and the parameters (ε 0 , ε 1 , β 0 , β 1 , γ 0 , γ 1 , p). 
     The formula, as shown below with reference to  FIG.  1   , does not make the diameters of the various segment explicit and is applicable to all smoothbore calibers. 
     
       
         
           
             f 
             ( 
             x 
             ) 
             
               
                 
                   
                     
                       
                         D 
                         − 
                         
                           x 
                           L 
                         
                         ⋅ 
                         ( 
                         D 
                         − 
                         H 
                         ) 
                       
                     
                     
                       
                         0 
                         ≤ 
                         x 
                         ≤ 
                         L 
                       
                     
                   
                   
                     
                       
                         
                           ε 
                           0 
                         
                         H 
                         
                           
                             
                               e 
                               0 
                             
                             − 
                             
                               
                                 x 
                                 − 
                                 L 
                               
                               
                                 ( 
                                 
                                   x 
                                   2 
                                 
                                 − 
                                 L 
                                 ) 
                               
                             
                             ( 
                             
                               e 
                               0 
                             
                             − 
                             
                               β 
                               1 
                             
                             ) 
                           
                         
                       
                     
                     
                       
                         L 
                         ≤ 
                         x 
                         ≤ 
                         
                           x 
                           2 
                         
                       
                     
                   
                   
                     
                       
                         
                           ε 
                           1 
                         
                         H 
                         
                           
                             
                               β 
                               1 
                             
                             
                                 
                               
                                 
                                   ε 
                                   0 
                                 
                               
                             
                             − 
                             
                               
                                 x 
                                 − 
                                 
                                   x 
                                   2 
                                 
                               
                               
                                 ( 
                                 
                                   x 
                                   3 
                                 
                                 − 
                                 
                                   x 
                                   2 
                                 
                                 ) 
                               
                             
                             ( 
                             
                               β 
                               1 
                             
                             
                                 
                               
                                 
                                   ε 
                                   0 
                                 
                               
                             
                             − 
                             
                               β 
                               0 
                             
                             ) 
                           
                         
                       
                     
                     
                       
                         
                           x 
                           2 
                         
                         ≤ 
                         x 
                         ≤ 
                         
                           x 
                           3 
                         
                       
                     
                   
                   
                     
                       
                         ( 
                         
                           ε 
                           1 
                         
                         
                           β 
                           0 
                         
                         + 
                         
                           ε 
                           0 
                         
                         
                           β 
                           1 
                         
                         − 
                         
                           ε 
                           0 
                         
                         
                           ε 
                           1 
                         
                         
                           β 
                           1 
                         
                         ) 
                         H 
                       
                     
                     
                       
                         
                           x 
                           3 
                         
                         ≤ 
                         x 
                         ≤ 
                         
                           x 
                           4 
                         
                       
                     
                   
                   
                     
                       
                         ( 
                         
                           ε 
                           1 
                         
                         
                           γ 
                           0 
                         
                         + 
                         
                           γ 
                           1 
                         
                         
                           ε 
                           0 
                         
                         − 
                         
                           ε 
                           0 
                         
                         
                           ε 
                           1 
                         
                         
                           γ 
                           1 
                         
                         ) 
                         H 
                       
                     
                     
                       
                         
                           x 
                           4 
                         
                         ≤ 
                         x 
                         ≤ 
                         
                           x 
                           5 
                         
                       
                     
                   
                   
                     
                       
                         ( 
                         
                           ε 
                           1 
                         
                         
                           γ 
                           0 
                         
                         + 
                         
                           γ 
                           1 
                         
                         
                           ε 
                           0 
                         
                         − 
                         
                           ε 
                           0 
                         
                         
                           ε 
                           1 
                         
                         
                           γ 
                           1 
                         
                         ) 
                         H 
                         − 
                         
                           
                             x 
                             − 
                             
                               x 
                               5 
                             
                           
                           
                             
                               x 
                               6 
                             
                             − 
                             
                               x 
                               5 
                             
                           
                         
                         ⋅ 
                         ( 
                         ( 
                         
                           ε 
                           1 
                         
                         
                           γ 
                           0 
                         
                         + 
                         
                           γ 
                           1 
                         
                         
                           ε 
                           0 
                         
                         − 
                         
                           ε 
                           0 
                         
                         
                           ε 
                           1 
                         
                         
                           γ 
                           1 
                         
                         ) 
                         H 
                         − 
                         ρ 
                         ( 
                         
                           ε 
                           1 
                         
                         
                           β 
                           0 
                         
                         + 
                         
                           ε 
                           0 
                         
                         
                           β 
                           1 
                         
                         − 
                         
                           ε 
                           0 
                         
                         
                           ε 
                           1 
                         
                         
                           β 
                           1 
                         
                         ) 
                         H 
                         ) 
                       
                     
                     
                       
                         
                           x 
                           5 
                         
                         ≤ 
                         x 
                         ≤ 
                         
                           x 
                           6 
                         
                       
                     
                   
                   
                     
                       
                         ρ 
                         ( 
                         
                           ε 
                           1 
                         
                         
                           β 
                           0 
                         
                         + 
                         
                           ε 
                           0 
                         
                         
                           β 
                           1 
                         
                         − 
                         
                           ε 
                           0 
                         
                         
                           ε 
                           1 
                         
                         
                           β 
                           1 
                         
                         ) 
                         H 
                       
                     
                     
                       
                         
                           x 
                           6 
                         
                         ≤ 
                         x 
                         ≤ 
                         
                           x 
                           7 
                         
                       
                     
                   
                 
               
             
           
         
       
     
     According to the C.I.P. standard, the parameters related to the cartridge chamber are defined as follows:
     D: diameter at chamber mouth;   H: diameter at end of chamber;   L: chamber length.   

     The other parameters mentioned in the above cited formula are defined as follows:
     ε 0 : topological divergence coefficient; it can only assume the values “0” and “1”;   ε 1 : topological convergence coefficient; it can only assume the values “0” and “1”;   β 0 : convergence coefficient; this is the ratio between the bore diameter (d b ) and the diameter at end of chamber (H) (convergent and divergent-convergent case);   β 1 : divergence coefficient; this is the ratio between the bore diameter (d b ) and the diameter at end of chamber (H) (divergent case); β 1  is greater than β 0 ;   γ 0 : expansion coefficient; this is the ratio between the diameter of the segment having an increased diameter (d ob ) and the diameter at end of chamber (H) (convergent and divergent-convergent case);   γ 1 : expansion coefficient; this is the ratio between the diameter of the segment having an increased diameter (d ob ) and the diameter at end of chamber (H) (divergent case); γ 1  is greater than γ 0 ;   p: choke coefficient; this is the ratio between the outlet diameter and the bore diameter β 0  or β 1 .   

     The internal profile of the barrel  1 , according to the present invention, may assume three different shapes as the parameters ε 0 , ε 1  vary, as exemplified in  FIGS.  2 - 4   . 
       FIG.  2    shows a profile with divergent-convergent configuration, in which ε 0  = 1, ε 1  = 1, X 1  ≠ X 2  ≠ X 3 . 
       FIG.  3    shows a profile with convergent configuration, in which ε 0  = 0, ε 1  =  1 , X 1  = X 2 . 
       FIG.  4    shows a profile with divergent configuration, in which ε 0  = 1, ε 1  = 0, X 2  = X 3 . 
     Advantageously, the above formula is valid for all smoothbore calibers. 
     The barrel assembly according to the present invention allows to obtain all the advantageous features indicated hereinafter with great advantage over barrels of the background art, which are each capable of providing only a portion of the desirable characteristics. 
     The barrel assembly according to the present invention allows a higher shot speed at any distance comprised between the muzzle and the range. This ensures the possibility to reduce the anticipation and aim directly at the target. 
     A further characteristic of the present barrel assembly is constituted by higher penetration energy, with the advantage of increased arresting power. 
     A further characteristic of the present barrel assembly is the increased range, which allows for an increase in the useful firing distance. 
     A further characteristic of the present barrel assembly is the improved ballistic performance, with both shot cartridges (lead and “lead free” materials) and ball cartridges, offering the advantage of increased ballistic performance regardless of the ammunition used. 
     An additional characteristic of the present barrel assembly is constituted by the fact that it eliminates the choke constraints for “lead free” cartridges, which in traditional firearms are due to the standard chokes made of ordinary steel, which do not allow going beyond 3-star chokes. The new profile of the barrel assembly according to the present invention allows to overcome this limitation and have different shot patterns with different types of choke; for example, shot patterns corresponding to full (1-star) chokes with a standard 3-star choke. 
     The innovative spread produced by the new barrel profile according to the present invention offers the advantage of reducing manufacturing limitations, i.e., the relationship between the material and the choke ratio, that are typical of traditional standard barrels. 
     A further characteristic of the present barrel assembly resides in that it reduces the pressure variation at barrel exit, since the new internal profile allows to increase the speed in the end part of the barrel, resulting in reduced local pressure. This offers the advantage of producing less noise on firing. 
     A further advantageous characteristic of the present barrel assembly is the reduced recoiling force. 
       FIGS.  5  and  6    schematically show the test methods and the results obtained with the barrel assembly according to the present invention, compared with traditional systems. 
     Advantageously, the barrel assembly according to the present invention can be made in modular form, as described below. 
     According to an aspect of the present invention, the adjustable barrel assembly is constituted by three basic components: a barrel body  101 , an extension  120 , an inner choke member  130 , and/or an outer choke member  140 , shown schematically in  FIG.  7   . 
     According to an aspect of the invention, the barrel assembly is provided with a configuration without a choke member, i.e., with a choke provided in the barrel body itself. 
     In this embodiment, the barrel assembly is not adapted to allow adjustment, due to the absence of a muzzle thread, but is designed to provide the shooter with the best ballistic performance/penetration force, while keeping the barrel length constant. 
     The internal geometry of the barrel is defined by acting on the following sections:
     1. length of the chamber/bore conical blending portion;   2. bore diameter, which can be constant, increasing, decreasing or “combined” (e.g., increasing + constant + decreasing);   3. length and type of fixed choke, which can be constant, increasing, decreasing or “combined”, e.g.: increasing + constant + decreasing.   

     According to a further aspect of the invention, the barrel assembly is provided with a configuration having an inner choke member; this barrel, designated by the reference numeral  200 , is shown in  FIG.  8   . 
     In this case, the barrel  200  is adapted to allow adjustment by means of a muzzle thread. 
     This configuration includes two components, the barrel  101  and the inner choke member  130 , and allows to reach a minimum barrel length. 
     Considering that the inside diameter of each component can be provided in four ways (constant, increasing, decreasing or combined), it follows that the total number of configurations that can be provided with this type of barrel + inner choke is sixteen, using four barrels and four inner chokes, for a total of eight components: 
     
       
         
           
               
               
               
               
             
               
                 ID 
                 BARREL PROFILE 
                 INNER CHOKE PROFILE 
                 BARREL LENGTH 
               
             
            
               
                 1 
                 CONSTANT 
                 CONSTANT 
                 MINIMUM 
               
               
                 2 
                 INCREASING 
               
               
                 3 
                 DECREASING 
               
               
                 4 
                 COMBINED 
               
               
                 5 
                 INCREASING 
                 CONSTANT 
               
               
                 6 
                 INCREASING 
               
               
                 7 
                 DECREASING 
                   
               
               
                 8 
                 COMBINED 
               
               
                 9 
                 DECREASING 
                 CONSTANT 
               
               
                 10 
                 INCREASING 
               
               
                 11 
                 DECREASING 
               
               
                 12 
                 COMBINED 
               
               
                 13 
                 COMBINED 
                 CONSTANT 
               
               
                 14 
                 INCREASING 
               
               
                 15 
                 DECREASING 
               
               
                 16 
                 COMBINED 
               
            
           
         
       
     
     According to a further aspect of the invention, the barrel assembly is provided with a configuration having an outer choke member; this barrel assembly, designated by the reference numeral  300 , is shown in  FIG.  10   . 
     This barrel assembly is designed to allow adjustment, by means of the muzzle thread, and is the same one as in the previous example. 
     This configuration includes two components: the barrel  101  and the outer choke  140 , allowing to reach a medium barrel length, referenced here as “MEDIUM Type 1”. 
     Since the inside diameter of each component can be provided in four ways (constant, increasing, divergent or combined), it follows that the total number of configurations, that can be provided with this type of barrel with outer choke, is sixteen, using four barrels and four outer chokes, for a total of eight components. 
     
       
         
           
               
               
               
               
             
               
                 ID 
                 BARREL PROFILE 
                 OUTER CHOKE PROFILE 
                 BARREL LENGTH 
               
             
            
               
                 1 
                 CONSTANT 
                 CONSTANT 
                 MEDIUM Type 1 
               
               
                 2 
                 INCREASING 
               
               
                 3 
                 DECREASING 
               
               
                 4 
                 COMBINED 
               
               
                 5 
                 INCREASING 
                 CONSTANT 
               
               
                 6 
                 INCREASING 
               
               
                 7 
                 DECREASING 
               
               
                 8 
                 COMBINED 
               
               
                 9 
                 DECREASING 
                 CONSTANT 
               
               
                 10 
                 INCREASING 
               
               
                 11 
                 DECREASING 
               
               
                 12 
                 COMBINED 
               
               
                 13 
                 COMBINED 
                 CONSTANT 
               
               
                 14 
                 INCREASING 
               
               
                 15 
                 DECREASING 
               
               
                 16 
                 COMBINED 
               
            
           
         
       
     
     According to a further aspect of the invention, the barrel assembly is provided with a configuration having an extension and an inner choke member; this barrel assembly, designated by the reference numeral  400 , is shown in  FIG.  9   . 
     In this case, the barrel assembly is adapted to be adjustable, by means of the muzzle thread, and is the same one as in the previous example. 
     This configuration includes three components: the barrel  101 , the extension  120 , and the inner choke  130 , and allows to reach a medium barrel length, referenced here as “MEDIUM Type 2”. 
     Since the inside diameter of each component can be provided in four ways (constant, increasing, decreasing or “combined”), it follows that the total number of configurations that can be provided with this type of assembly, barrel + extension + inner choke, is sixty-four using a total of twelve components (four barrels, four extensions and four inner chokes). 
     
       
         
           
               
               
               
               
               
             
               
                 ID 
                 BARREL PROFILE 
                 EXTENSION PROFILE 
                 INNER CHOKE PROFILE 
                 BARREL LENGTH 
               
             
            
               
                 1 
                 CONSTANT 
                 CONSTANT 
                 CONSTANT 
                 MEDIUM Type 2 
               
               
                 2 
                 INCREASING 
               
               
                 3 
                 DECREASING 
               
               
                 4 
                 COMBINED 
               
               
                 5 
                 INCREASING 
                 CONSTANT 
               
               
                 6 
                 INCREASING 
               
               
                 7 
                 DECREASING 
               
               
                 8 
                 COMBINED 
               
               
                 9 
                   
                 DECREASING 
                 CONSTANT 
                   
               
               
                 10 
                 INCREASING 
               
               
                 11 
                 DECREASING 
               
               
                 12 
                 COMBINED 
               
               
                 13 
                 COMBINED 
                 CONSTANT 
               
               
                 14 
                 INCREASING 
               
               
                 15 
                 DECREASING 
               
               
                 16 
                 COMBINED 
               
               
                 17 
                 INCREASING 
                 CONSTANT 
                 CONSTANT 
               
               
                 18 
                 INCREASING 
               
               
                 19 
                 DECREASING 
               
               
                 20 
                 COMBINED 
               
               
                 21 
                 INCREASING 
                 CONSTANT 
               
               
                 22 
                 INCREASING 
               
               
                 23 
                 DECREASING 
               
               
                 24 
                 COMBINED 
               
               
                 25 
                 DECREASING 
                 CONSTANT 
               
               
                 26 
                 INCREASING 
               
               
                 27 
                 DECREASING 
               
               
                 28 
                 COMBINED 
               
               
                 29 
                   
                 COMBINED 
                 CONSTANT 
                   
               
               
                 30 
                 INCREASING 
               
               
                 31 
                 DECREASING 
               
               
                 32 
                 COMBINED 
               
               
                 33 
                 DECREASING 
                 CONSTANT 
                 CONSTANT 
               
               
                 34 
                 INCREASING 
               
               
                 35 
                 DECREASING 
               
               
                 36 
                 COMBINED 
               
               
                 37 
                 INCREASING 
                 CONSTANT 
               
               
                 38 
                 INCREASING 
               
               
                 39 
                 DECREASING 
               
               
                 40 
                 COMBINED 
               
               
                 41 
                 DECREASING 
                 CONSTANT 
               
               
                 42 
                 INCREASING 
               
               
                 43 
                 DECREASING 
               
               
                 44 
                 COMBINED 
               
               
                 45 
                 COMBINED 
                 CONSTANT 
               
               
                 46 
                 INCREASING 
               
               
                 47 
                 DECREASING 
               
               
                 48 
                 COMBINED 
               
               
                 49 
                 COMBINED 
                 CONSTANT 
                 CONSTANT 
                   
               
               
                 50 
                 INCREASING 
               
               
                 51 
                 DECREASING 
               
               
                 52 
                 COMBINED 
               
               
                 53 
                 INCREASING 
                 CONSTANT 
               
               
                 54 
                 INCREASING 
               
               
                 55 
                 DECREASING 
               
               
                 56 
                 COMBINED 
               
               
                 57 
                 DECREASING 
                 CONSTANT 
               
               
                 58 
                 INCREASING 
               
               
                 59 
                 DECREASING 
               
               
                 60 
                 COMBINED 
               
               
                 61 
                 COMBINED 
                 CONSTANT 
               
               
                 62 
                 INCREASING 
               
               
                 63 
                 DECREASING 
               
               
                 64 
                 COMBINED 
               
            
           
         
       
     
     By disassembling the extension  120  it is possible to reduce the barrel length from “MEDIUM Type2” to “MINIMUM”, which corresponds to the previous configuration, designated by the reference numeral  200 , which allows to have sixteen more configurations. 
     In summary, with twelve components (four barrels, four extensions and four inner chokes) it is possible to have:
     sixty-four configurations with “MEDIUM Type 2” barrel length   sixteen configurations with “MINIMUM” barrel length.   

     According to a further aspect of the invention, the barrel assembly is provided with a configuration having an extension and an outer choke member; this barrel assembly, designated by the reference numeral  500 , is shown in  FIG.  11   . 
     In this case, the barrel assembly is designed to be adjustable, by means of the muzzle thread, and is the same one as in the previous example. 
     This configuration has three components: the barrel  101 , the extension  120  and the outer choke  140 , allowing to reach the maximum barrel length. 
     Considering that the inside diameter of each component can be provided in four ways (constant, increasing, decreasing or combined), it follows that the total number of configurations that can be provided with this type of barrel with extension and outer choke is sixty-four, using a total of twelve components (four barrels, four extensions and four outer chokes). 
     
       
         
           
               
               
               
               
               
             
               
                 ID 
                 BARREL PROFILE 
                 EXTENSION PROFILE 
                 OUTER CHOKE PROFILE 
                 BARREL LENGTH 
               
             
            
               
                 1 
                 CONSTANT 
                 CONSTANT 
                 CONSTANT 
                 MAXIMUM 
               
               
                 2 
                 INCREASING 
               
               
                 3 
                 DECREASING 
               
               
                 4 
                 COMBINED 
               
               
                 5 
                   
                 INCREASING 
                 CONSTANT 
                   
               
               
                 6 
                 INCREASING 
               
               
                 7 
                 DECREASING 
               
               
                 8 
                 COMBINED 
               
               
                 9 
                 DECREASING 
                 CONSTANT 
               
               
                 10 
                 INCREASING 
               
               
                 11 
                 DECREASING 
               
               
                 12 
                 COMBINED 
               
               
                 13 
                 COMBINED 
                 CONSTANT 
               
               
                 14 
                 INCREASING 
               
               
                 15 
                 DECREASING 
               
               
                 16 
                 COMBINED 
               
               
                 17 
                 INCREASING 
                 CONSTANT 
                 CONSTANT 
               
               
                 18 
                 INCREASING 
               
               
                 19 
                 DECREASING 
               
               
                 20 
                 COMBINED 
               
               
                 21 
                 INCREASING 
                 CONSTANT 
               
               
                 22 
                 INCREASING 
               
               
                 23 
                 DECREASING 
               
               
                 24 
                 COMBINED 
               
               
                 25 
                   
                 DECREASING 
                 CONSTANT 
                   
               
               
                 26 
                 INCREASING 
               
               
                 27 
                 DECREASING 
               
               
                 28 
                 COMBINED 
               
               
                 29 
                 COMBINED 
                 CONSTANT 
               
               
                 30 
                 INCREASING 
               
               
                 31 
                 DECREASING 
               
               
                 32 
                 COMBINED 
               
               
                 33 
                 DECREASING 
                 CONSTANT 
                 CONSTANT 
               
               
                 34 
                 INCREASING 
               
               
                 35 
                 DECREASING 
               
               
                 36 
                 COMBINED 
               
               
                 37 
                 INCREASING 
                 CONSTANT 
               
               
                 38 
                 INCREASING 
               
               
                 39 
                 DECREASING 
               
               
                 40 
                 COMBINED 
               
               
                 41 
                 DECREASING 
                 CONSTANT 
               
               
                 42 
                 INCREASING 
               
               
                 43 
                 DECREASING 
               
               
                 44 
                 COMBINED 
               
               
                 45 
                 COMBINED 
                 CONSTANT 
                   
               
               
                 46 
                 INCREASING 
               
               
                 47 
                 DECREASING 
               
               
                 48 
                 COMBINED 
               
               
                 49 
                 COMBINED 
                 CONSTANT 
                 CONSTANT 
               
               
                 50 
                 INCREASING 
               
               
                 51 
                 DECREASING 
               
               
                 52 
                 COMBINED 
               
               
                 53 
                 INCREASING 
                 CONSTANT 
               
               
                 54 
                 INCREASING 
               
               
                 55 
                 DECREASING 
               
               
                 56 
                 COMBINED 
               
               
                 57 
                 DECREASING 
                 CONSTANT 
               
               
                 58 
                 INCREASING 
               
               
                 59 
                 DECREASING 
               
               
                 60 
                 COMBINED 
               
               
                 61 
                 COMBINED 
                 CONSTANT 
               
               
                 62 
                 INCREASING 
               
               
                 63 
                 DECREASING 
               
               
                 64 
                 COMBINED 
               
            
           
         
       
     
     Starting from the complete configuration, the replacement of the outer choke  140  with the inner choke  130  allows to reduce the barrel length from maximum to “MEDIUM Type 2”, which corresponds to the previous configuration, which allows to have sixty-four configurations more. 
     Starting from the complete configuration, by disassembling only the central extension  120  it is possible to reduce the barrel length from maximum to “MEDIUM Type 1”, which corresponds to the previous configuration, which allows to have sixteen configurations more. 
     Starting from the complete configuration, by disassembling the extension  120  and replacing the outer choke  140  with the inner choke  130  it is possible to reduce the barrel length from maximum to minimum, which corresponds to the previous configuration, which allows to have sixteen configurations more. 
     In summary, with sixteen components (four barrels, four extensions, four inner chokes and four outer chokes) it is possible to have:
     sixty-four configurations with maximum barrel length   sixty-four configurations with “MEDIUM Type 2” barrel length   sixteen configurations with “MEDIUM Type 1” barrel length   sixteen configurations with minimum barrel length.   

     Advantageously, the barrel assembly according to the present invention can be provided monolithically or in a double configuration, according to the teachings of European Patent EP2541187B1. 
     An important advantage of the double barrel is to make it possible to produce all the standard lengths using the same tube  102 , with a considerable manufacturing advantage. 
     By way of example,  FIGS.  12 ,  13 ,  14    respectively show 3.5″, 3″, 2¾″ powder chambers, however, other lengths can also be advantageously used, for example 1.75″. 
     According to a further aspect of the present invention, the present barrel assembly can advantageously be provided with different solutions of aiming members in order to allow easy and quick aiming, without interfering with the added modular members. 
     The barrel assembly may have a sight holder and a muzzle sight, a rib, made of metal, carbon fiber or other materials, a sight notch, a secondary rib. 
     In practice it has been found that the invention achieves the intended aim and objects, providing a new gun barrel assembly that ensures a combination of advantageous functional characteristics, confirmed by numerous experimental tests concerning speed measured at twenty meters, shot penetration, and ballistic tests with both shot and ball cartridges. 
     The new internal profile of the barrel assembly according to the present invention is the result of a fluid dynamics study aimed at maximizing the previously described advantages by considering these aspects:
     the subsonic/transonic/supersonic flow that is present inside the barrel depending on the type of bullet used (e.g., a subsonic flow accelerates in a convergent duct, a supersonic flow accelerates in a divergent duct);   Bernoulli’s theorem and minimization of distributed and localized load losses within the barrel;   maximization of the barrel bore, far beyond that currently considered/provided by competitors (for a 12 gauge it is approximately 19.6 mm vs. the standard 18.4 - 18.8 mm);   maximization of the segment with increased diameter (localized volume increase in the muzzle), well beyond that currently considered/provided by competitors (for a 12 gauge it can exceed 21.3 mm, the maximum value of case no. 3 of Italian Patent IT1405143, which does not, however, provide for the initial conical blending portion).   

     The gun barrel assembly according to the present invention offers a whole series of important advantages, unlike the prior art barrels, none of which is able to provide a combination of all the aforementioned advantages. 
     The gun barrel assembly according to the present invention allows higher shot speed at any distance comprised between the muzzle and the range, allowing to reduce the anticipation and aim directly at the target. 
     The barrel according to the invention provides a higher penetration energy, increasing the arresting power. 
     The barrel according to the invention offers a greater range, increasing the useful firing distance. 
     The barrel according to the invention offers improved ballistic performance with both shot cartridges (lead and “lead free” materials) and ball cartridges, increasing ballistic performance regardless of the ammunition used. 
     The barrel according to the invention eliminates current choke constraints for “lead free” cartridges. Currently, with “standard” chokes made of ordinary steel one cannot go beyond 3-star chokes: the new barrel profile allows to overcome this limitation and have shot patterns corresponding to full (1-star) chokes with a standard 3-star choke. This makes it possible to reduce the manufacturing limits (relationship between the material and the choke ratio) currently present in standard barrels thanks to the innovative spread produced by the new barrel profile. 
     The barrel according to the present invention reduces the pressure variation at barrel exit by virtue of the new internal profile, which allows to increase the speed in the end part of the barrel, with consequent local pressure reduction, reducing noise on firing. 
     A further advantage of the barrel according to the present invention is constituted by recoil reduction. 
     The modular construction of the barrel according to the present invention offers the advantage of eliminating or at least considerably reducing the technological constraints that current barrels of the traditional type provided by hammering or boring. 
     A further advantage of the modular barrel is that of providing the user with a barrel of variable length, depending on the type of sports/hunting use. 
     A further advantage of the modular barrel is the possibility to reduce barrel production/management and purchase costs. 
     This application claims the priority of Italian Patent Application No. 102021000028739, filed on Nov. 11, 2021, the subject matter of which is incorporated herein by reference.