Firearm barrel cooling system

A firearm barrel cooling system includes fins formed to extend around and from a barrel blank of a same material as the fins. An outside major diameter of the fins is greater than an outside diameter of the formed barrel near a shank of the barrel. Flutes are defined around and in the barrel blank between adjacent fins wherein an outside diameter of the flutes is equal to a minor diameter of the fins and equal to or greater than an outside diameter of the barrel. A transition from a crest of a flute to a base of a fin coincides with a taper of the formed barrel from shank to muzzle. Fin cooling sections are located between a barrel collar and a muzzle end of the formed barrel, each cooling section having a plurality of fins. A method for cooling a firearm barrel system therefore is also included herein.

BACKGROUND OF THE INVENTION

Weapons like the AR15/M16/M4 are capable of firing in full automatic mode but seldom are for various reasons. Chief among those reasons is the rapid accumulation of heat first in the barrel and then throughout the rest of the firing mechanisms. Among the problems caused by accumulated heat not being rejected from the rifle are: (1) thermal expansion causing lock up of the metal pieces in the mechanisms that extract spent shells from the chamber and load new shells from the magazine, (2) auto-discharge of the cartridge when loaded into the hot chamber without the firing pin striking the cartridge primer (aka ‘cook-off’), (3) rupture of the weakened barrel and (4) rupture of the weakened gas tube, which transfers hot combustion gases from the barrel first through the gas block and then into the upper receiver to cycle the action.

Designing a rifle to ameliorate elevating barrel temperatures has in the past conflicted with the need for a light weight rifle that can be readily carried by a single person. A major portion of the total rifle weight, which ranges from 6 to 8 pounds for AR15/M16/M4, is contributed by the barrel itself. Elevated barrel temperatures also cause severe degradation in rifle accuracy. As the metal barrel gets hot, it becomes less rigid, flexing more when fired and causing the bullet trajectory to be erratic. Further complicating the design of a barrel cooling system for weapons like the AR15/M16/M4 is the size, function and location of the gas block, which is located typically near the midpoint of the barrel overall length.

SUMMARY OF THE INVENTION

A firearm barrel cooling system comprising a plurality of fins adapted to extend around and formed from a solid barrel blank of a same material as the fins is disclosed. An outside major diameter of the fins is greater than an outside diameter of the barrel at any point of the barrel. A plurality of flutes are defined around and in the one piece formed barrel between adjacent fins wherein an inside diameter of the flutes is less than the outside diameter of the formed barrel.

Also, a plurality of flutes are defined around and in the one piece formed barrel between adjacent fins wherein an inside diameter of the fins is equal to a minor diameter of the fins and less than an outside diameter of the formed barrel. A plurality of cooling sections are located between a barrel collar and a muzzle end of the one piece formed barrel, each cooling section having a plurality of fins having a major outer diameter and a minor inner diameter.

A firearm barrel cooling method comprising forming a plurality of fins adapted to extend around and above a one-piece barrel blank of a same material as the fins wherein an outside major diameter of the fins is greater than an outside diameter of the formed barrel at any point of the formed barrel. The method also includes forming a plurality of flutes defined around and in the one-piece formed barrel between adjacent fins wherein an inside diameter of the flutes is equal to a minor diameter of the fins and less than an outside diameter of the formed barrel. The method additionally includes forming a plurality of cooling sections between a barrel collar and a muzzle end of the one-piece formed barrel, each cooling section having a plurality of fins having a major outer diameter and a minor inner diameter.

Other aspects and advantages of embodiments of the disclosure will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrated by way of example of the principles of the disclosure.

Throughout the description, similar or same reference numbers may be used to identify similar or same elements in the several embodiments and drawings. Although specific embodiments of the invention have been illustrated, the invention is not to be limited to the specific forms or arrangements of parts so described and illustrated. The scope of the invention is to be defined by the claims appended hereto and their equivalents.

DETAILED DESCRIPTION

Reference will now be made to exemplary embodiments illustrated in the drawings and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Alterations and further modifications of the inventive features illustrated herein and additional applications of the principles of the inventions as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the invention. The term ‘nominal’ used throughout the disclosure is in reference to a common definition of the term meaning of or relating to a designated or theoretical size that may vary from the actual size or dimension. Also, the term ‘inverted fin’ and the term ‘flute,’ refers to a cavity, an ‘inverted fin’ or space between fins and is therefore synonymous throughout the disclosure with the terms ‘cavity,’ ‘cavities’ and ‘space’ though more descriptive than either synonymous term. The term ‘barrel blank’ refers to a blank stock before machining per the disclosure to a ‘formed barrel’ including fins and flutes. The terms ‘blank stock,’ ‘barrel blank,’ ‘blank barrel,’ ‘blank barrel stock,’ are synonymous throughout the disclosure. The term ‘divot’ refers to a common definition of the term as a piece of material cut out of stock by making a cutting stroke.

This present application discloses barrel designs and passive barrel cooling systems that: (1) rapidly reject or dissipate the combustion heat passed into the rifle barrel from discharge of the cartridge, (2) accommodate the location and function of the gas block, (3) reduce barrel weight in comparison to larger diameter, heavier ‘bull’ barrels, (4) ensure proper positioning of the barrel cooling system during installation, (5) maintain proper positioning of the barrel cooling system during firing and (6) insure the accuracy is maintained by attenuating barrel flex when the rifle is fired.

FIGS. 1 through 8illustrate a first example of this barrel cooling system.FIG. 1depicts a side view of the barrel system, Item10, from an AR15/M16/M4 pattern rifle. Item90is the barrel itself. Item92is the barrel lug or collar that abuts with the upper receiver of the rifle, which is not shown. Item94is the portion of the barrel immediately after the barrel lug. Item30is the gas block that receives a portion of the combustion gases, which are redirected through the gas tube, Item40, back toward the upper receiver to operate the mechanisms configured to eject a spent cartridge. Item99is the portion of the barrel at the gas block. The dimension at the bottom of opposing flutes, Item95, is nominally the same or slightly more than outside diameter of the barrel at the gas block location, Item99. Different than current barrel designs, with flutes that terminate before the gas block position, the flutes continue completely out to the gas block position, Item99. The fins that result from this flute design provide sufficient means to locate the gas block, Item30, along the barrel. Machining the flutes, Item95, into the exterior of the barrel and all the way out to the gas block position maximizes the length of the flutes and reduces barrel weight without compromising barrel strength.

FIG. 2illustrates a side view of the arc shaped flutes, Item95, that have been cut down and into the barrel after the barrel lug. There are corresponding ribs, Item96, that result from the machining of these flutes, which are uniformly spaced around the barrel. The gas block has been removed for reasons of illustration and clarity.

FIG. 3illustrates a cross section, A-A, ofFIG. 2that depicts the barrel flutes, Item95, the barrel ribs, Item96, the barrel collar, Item92, the bore of the barrel, Item91, through which the bullets pass and other details of the barrel design. The machining of the flutes into the barrel is continuous to the location of the gas block, such that the vertical faces or ends of the ribs, Item96, as seen inFIG. 3can be used to position the gas block along the barrel.

FIG. 4illustrates a side view of the aluminum cooling extrusions, Item100, located in the fluted portion of the barrel. Same reference numbers may be used for same and similar components illustrated in other figures in the present disclosure.

FIG. 5illustrates a cross section, B-B, ofFIG. 4that depicts two aluminum cooling extrusions, Item100, in a conformal arrangement with the fluted portion of the barrel. Also illustrated inFIG. 5is a hand guard, Item50, that fully surrounds the barrel, barrel cooling extrusions and the gas tube. Although not shown in any other figure, the hand guard is extensively ventilated to allow heat to pass from the cooling extrusions to the surrounding air. The hand guard is an integral part of the rifle system and is not shown in any other figures for reasons of clarity.

FIG. 6illustrates a side view of the cooling extrusion, Item100. Same reference numbers may be used for same and similar components illustrated in other figures in the present disclosure.

FIG. 7illustrates an end view of two cooling extrusions removed from the conformal engagement with the fluted portion of the barrel. The interior surfaces of the cooling extrusion, Item105and Item106, correspond to the exterior surfaces of the fluted barrel, Item95and Item96, respectively. Cooling fins, Item102, are depicted inFIG. 7as well. These fins increase the surface area exposed to the atmosphere increasing heat transfer from and cooling of the barrel.

FIG. 8illustrates an end view of the two cooling extrusions having been attached to the fluted portion of the barrel. The cooling extrusions would be affixed to the barrel by pressure being exerted along its length and in toward the bore of the barrel. This pressure will spread or flex open the cooling extrusions until the dimensional obstruction between Item96and Item105, as seen inFIG. 7, is cleared and the cooling extrusion will snap into a conformal arrangement with the fluted barrel. This ‘one-way’ means of attachment precludes any external fasteners or other means of affixing the cooling extrusions to the fluted barrel.

Anticipated in this disclosure but not depicted, thermally conductive adhesives can also be used in the attachment of the cooling extrusions to the barrel to accommodate dimensional variances and maximize heat transfer performance. Thermally conductive adhesives are known in the semiconductor industry when heat sinks are attached to computer microprocessor chips.

FIGS. 9 through 14depict a second example of this barrel cooling system.FIG. 9is a side view that depicts a barrel system, Item20, from an AR15/M16/M4 pattern rifle. Item290is the barrel itself. Item292is the barrel lug or collar that abuts with the upper receiver of the rifle, which is not shown. Item294is the portion of the barrel immediately after the barrel lug. Item30is the gas block that receives a portion of the combustion gases, which are redirected through the gas tube, Item40, back toward the upper receiver to operate the mechanisms to eject a spent cartridge. Item299is the portion of the barrel after the gas block.

FIG. 10is a side view that illustrates eight uniform, flat faced surfaces, Item295, that have been cut into the barrel after the barrel lug. The diameter of the barrel, Item296, immediately prior to the octagonal portion of the barrel is nominally the same as the dimension between opposing parallel flats, Item295. The gas block has been removed for reasons of illustration and clarity.

FIG. 11depicts a cross section, C-C, fromFIG. 10that illustrates the uniform eight flat surfaces, Item295, that have been cut into the barrel after the barrel lug. The diameter of the barrel immediately prior to the octagonal portion of the barrel, Item296, is nominally the same as the dimension between two parallel flats, Item298. The bore of the barrel, Item291, through which the bullets pass and other details of the barrel design are also depicted.

FIG. 12is a side view that depicts another aluminum cooling extrusion, Item300, located on the octagonal portion of the barrel.

FIG. 13is a side view that depicts the aluminum cooling extrusion, Item300, and the gas tube, Item40, removed from the barrel inFIG. 12.

FIG. 14depicts a cross section D-D, fromFIG. 13that illustrates the eight internal uniform flat surfaces, Item395, that would be in conformal contact with the external octagonal flats, Item295, when the aluminum cooling extrusion, Item300, has been installed on the barrel. Cooling fins, Item302, are also depicted inFIG. 14. These fins increase the surface area exposed to the atmosphere increasing heat transfer from and cooling of the barrel.

The distance between opposing internal flat surfaces, Item398, of the closed loop aluminum cooling extrusion, Item300, is slightly less than the distance across opposing flats of the barrel, Item298. The difference between Item298and Item398allows for an interference fit between the aluminum cooling extrusion and the barrel. Installation of the cooling extrusion over the octagonal portion of the barrel can be accomplished by mechanical means by pressing the aluminum extrusion over the barrel or by preheating the aluminum extrusion sufficient enough for the internal dimension, Item398, to grow greater than the external dimension, Item298, allowing the aluminum extrusion to slip over the ambient temperature barrel. As the aluminum cools it will exert a compression force rigidly affixing it to the barrel. Mechanical press fitting and thermal shrink fitting are common techniques in industry.

The distance between opposing flat surfaces, Item398, could be slightly greater than Item298and thermally conductive adhesives used to firmly affix Item300to Item290.

The non-circular, conformal surfaces of the barrel cooler extrusions in conjunction with the corresponding barrel surfaces insure proper orientation and location when being installed. Maintaining proper orientation and location of the cooling extrusion(s) while in use are important to prevent movement of the cooling extrusion under severe heating and potential interference with the gas tube, which is positioned near to the external surface of the barrel.

Circular internal cross section of a closed loop barrel cooler extrusion to be engaged with a circular external cross section of the barrel between the barrel lug and the gas block is also anticipated in this disclosure. Such a configuration would require fixed positioning of the cooling extrusion in correlation with the barrel when being installed to prevent interference with the gas tube. The internal ID of any single piece cooling extrusion, whether circular or not, must be greater than any barrel outside dimension after the gas block to allow the extrusion to be installed on the portion of the barrel between the barrel collar and the gas block.

The above descriptions herein also anticipate a closed loop barrel cooler fully underneath a straight gas tube exiting the gas block and entering the upper receiver without the familiar bend used to tuck the gas tube within the original hand guard of the M16. This arrangement allows for the barrel cooler to be installed without concern for interference with the gas tube.

FIG. 15depicts a side view of the barrel, Item400, configured with circular outside diameters to incorporate closed loop barrel coolers. Item35depicts the gas block with gas tube, Item45, exiting slightly higher than typical, running parallel with the barrel, entering into the upper receiver without any bends in the gas tube. Portions of the barrel, Item400, are shown in phantom with dashed lines. Item490is an end view of the barrel only with the various decreasing diameters from the upper receiver towards the muzzle. Item500depicts the closed loop barrel cooler affixed to the barrel between the upper receiver and the gas block. Item600depicts the closed loop barrel cooler affixed to the barrel after the gas block. The inside diameter of Item500would be slightly bigger than the inside diameter of Item600. This relationship allows for barrel cooler, Item500, to slip easily over portion of the barrel, Item400, where the gas block, Item35, and different barrel cooler, Item600, would be located.

FIG. 16depicts Item500removed from the barrel. Item590is a cross section E-E of Item500indicating longitudinal fins that run parallel to the barrel bore. In addition to being extruded, Item500could be machined from solid bar with fins that spiral around the barrel bore.

FIG. 17depicts Item600removed from the barrel. Item690is a cross section F-F of Item600indicating longitudinal fins that run parallel to the barrel bore. In addition to being extruded, Item600could be machined from solid bar with fins that spiral around the barrel bore.

FIG. 18depicts Item700removed from the barrel. Item790is a cross section E-E of Item700indicating circumferential fins or rings around the barrel bore. Item700could be machined from solid bar as a single unit or numerous units affixed around the barrel. Item700and any of the other variations of the closed loop barrel cooler depicted and anticipated herein could be constructed from various materials and methods such as foamed copper, foamed aluminum, metal injection molded copper or steel, sintered copper, machined beryllium copper and others.

The barrel cooling system(s) using aluminum devices attached to the steel barrel, as illustrated and described herein above, anticipate the following sequence of assembly: (1) insert the barrel nut over the barrel up to the barrel collar, (2) affix the aluminum barrel cooling devices to the barrel, (3) affix the barrel to the upper receiver with the barrel nut, (4) affix the gas block at the gas block position and correspondingly the gas tube to and through the barrel nut, (5) attach the free floating hand guard, encompassing the barrel, barrel cooling system, gas tube and gas block, over and to the barrel nut.

FIGS. 19 through 26depict barrel cooling systems that do not use aluminum cooling devices in conformal contact with the steel barrel as part of the heat transfer process. Aluminum does have a higher thermal conductivity than steel. However, aluminum has a significantly lower melting point and a higher coefficient of thermal expansion. In severe conditions of uninterrupted automatic firing, the accumulated heat in the barrel could cause the aluminum to melt, become loose, lift off from the conformal engagement with the barrel or other modes of malfunction.

FIGS. 19 through 26depict barrel cooling systems in which the cooling fins are common, of the same part with the barrel blank steel itself. The flutes are machined into and down from the nominal formed barrel outside diameter which itself is machined down from a barrel blank stock. This embodiment of the barrel cooling system utilizes cooling fins that extend below the barrel blank by virtue of the flutes and fins machined from the barrel blank stock in relief and therefore the fins extend above the nominal formed barrel outside diameter. This configuration results in a barrel cooling system without the different material properties and potential problems mentioned previously.

FIGS. 19 through 22illustrate a first example of the integral barrel cooling system. Item800is the barrel for an AR15/M16/M4 pattern rifle. Item802is the barrel lug or collar that abuts with the upper receiver of the rifle, which is not shown. Item804is the breech end of the barrel immediately after the barrel lug. Item35is the gas block that receives a portion of the combustion gases, which are redirected through the straight gas tube, Item45, back toward the upper receiver to operate the mechanisms to eject a spent cartridge. Item809is the portion of the barrel after the gas block.

Shown inFIG. 19is the barrel extension, Item810, with its threaded portion, Item815, having been removed from the breech end, Item804, of the barrel. The external threads, Item815, are used to attach the barrel extension, Item810, to the internal threads found within Item804. The barrel nut, Item816, has an internal diameter, Item817, slightly greater than the barrel at Item807.

The barrel cooling system using the integral, machined steel cooling fins as illustrated inFIGS. 19 through 22anticipates a different and unique sequence of assembly: (1) the barrel nut, Item816, first being located on or over the Item804portion of the barrel, (2) the barrel extension, Item810, then being screwed into the breech end, Item804, of the barrel and capturing the barrel nut, Item816, (3) the barrel, Item800, then being affixed to the upper receiver with the barrel nut, Item816, (4) the gas block, Item35, and gas tube, Item45, being affixed to the barrel and (5) free floating hand guard, not shown for reasons of clarity, located around and encompassing the barrel cooling system, gas tube and gas block.

FIG. 20illustrates a partial assembly of the barrel, Item800, with the barrel extension, Item810, gas block, Item35, and gas tube, Item45, installed. Barrel nut, Item816, is not shown for clarity.

FIG. 21illustrates Section G-G at the intersection of Item804with the commencement of the barrel cooling fins, Item830. The minor diameter of the cooling fins, Item835, is nominally the same as the barrel diameter at Item804.

FIG. 22illustrates Section H-H at the termination of the cooling fins, Item840, at the location of the gas block, Item35, and along the majority portion underneath the free floating handguard. The minor diameter of the cooling fins, Item845, for Section H-H would nominally be the same as the barrel diameter found at the gas block, Item35.

As illustrated inFIGS. 19 through 22, the barrel cooling fins are straight and nominally parallel with the bore axis of the barrel. Although not illustrated, this application anticipates the use of spiral cooling fin patterns and other patterns in the execution of the integral barrel cooling system.

FIGS. 23 through 26illustrate another example of the integral barrel cooling system. Item900is the barrel for an AR15/M16/M4 pattern rifle. Item902is the barrel lug or collar that abuts with the upper receiver of the rifle, which is not shown. Item904is the breech end portion of the barrel immediately after the barrel lug. Item35is the gas block that receives a portion of the combustion gases, which are redirected through the straight gas tube, Item45, back toward the upper receiver to operate the mechanisms to eject a spent cartridge. Item909is the portion of the barrel after the gas block.

Shown inFIG. 23is the barrel extension, Item910, with its threaded portion, Item915, having been removed from the breech end, Item904, of the barrel. The external threads, Item915, are used to attach the barrel extension, Item910, to the internal threads found within Item904. The barrel nut, Item916, has an internal diameter, Item917, slightly greater than the barrel at Item907.

The barrel cooling system using the integral machined steel cooling fins illustrated inFIGS. 23 through 26anticipates the different and unique sequence of assembly as described pertaining toFIGS. 19 through 22.

FIG. 24illustrates a partial assembly of the barrel, Item900, with the barrel extension, Item910, gas block, Item35, and gas tube, Item45, installed. Barrel nut, Item916, is not shown for clarity.

FIG. 25illustrates Section I-I at the end of Item904and the commencement of the first circumferential barrel cooling fin or circumferential rib, Item930. The minor diameter of the barrel cooling system, Item935, between the first three circumferential cooling rings, Item930, is nominally the same or slightly smaller than the barrel diameter at Item904.

FIG. 26illustrates Section J-J immediately prior to the last cooling fin or circumferential rib, Item930, just before the gas block, Item35. The minor diameter of the barrel cooling system, Item945, after Item935would be nominally the same as the barrel diameter for the gas block, Item35.

The descriptions herein and above for various barrel cooling methods apply to other rifle operating systems, such as the AK47/AK74/AKM, use gas operated piston and rod means to cycle the bolt mechanism when ejecting a spent cartridge. The space occupied by the operating rod would nominally be the same as occupied by the gas tube described herein.

FIG. 27illustrates a conventional blank barrel or blank stock, Item1000, configured for use in a bolt action rifle. The breech end of the barrel blank, Item1005, would be attached to the action that includes into the chamber and the bolt for removing spent cartridges from the chamber. Typical to bolt action rifles, the barrel blank outside diameter at the attachment to the action stays the same for a short distance, Item1010, before tapering down at the muzzle end of the barrel blank, Item1015. The taper1020is depicted from the breech end1005to the muzzle end1015.

FIG. 28illustrates a formed barrel, Item1100, configured for use in a bolt action rifle but also includes external cooling fins, Item1120, as similarly illustrated inFIGS. 19 through 22and flutes1125in accordance with an embodiment of the present disclosure. A barrel blank1000, not drawn to scale with respect toFIG. 28, without any fins or flutes is used to form the formed barrel1100. The start of flutes1130nearest the breech end1105of the formed barrel1100are depicted semicircular in elevation similar to the start of the flutes95inFIG. 2. A diameter of the flute starts1130is less than a diameter of the flutes1125and therefore the flutes1124have an intermediate diameter which sets up fins1123of decreasing width proximal the flute starts to a consistent width of the fins1120. The outside diameter1135of the breech end1105of the formed barrel1100and the major outside diameter of the fins1140are indicated. The inside diameter of the flutes is equal to the outside diameter1135minus the radius of the flute starts1130, also known as divots created by machining in relief from the barrel blank. The breech end1105of the formed barrel, Item1100would be attached to the action, which includes the chamber and bolt. Different than current bolt action rifle barrels, the larger diameter of the external cooling fins would preclude the use of common single piece wooden or molded plastic stocks that conform to the external profile of bolt action barrels as seen in Item1000ofFIG. 27. Chassis type rifle stocks that utilize free floating hand guards with sufficient internal diameter could be used to mount the finned barrel to the rifle action. Employing externally finned barrels would increase barrel stiffness and barrel cooling, benefiting the accuracy of bolt action rifles versus heavy bull barrels, while weighing less as well.

FIG. 29depicts a spiral fluted firearm cooling barrel configured to match the taper of a blank stock in accordance with an embodiment of the present disclosure. The depiction1110includes the breech end of the barrel1105, the muzzle end of the barrel1115, the fins1120, the flutes1125, the start of the flutes1130, the flute end divots1145created by machining in relief in the blank barrel and the intersection1150of the flutes1125with the fins1120. The flute to fin transition1150follows the taper of the barrel1020(similar to the taper depicted inFIG. 27) at any circumferential point on the barrel. The transition occurs at the intersection point of a base of a fin to the crest of a flute, depicted as the same point1150continuing along the taper of the barrel.

FIG. 30depicts a flow diagram for a firearm cooling method in accordance with an embodiment of the present disclosure. A firearm barrel cooling method comprises forming2010a plurality of fins adapted to extend around and from a one-piece barrel blank of a same material as the fins wherein an outside major diameter of the fins is greater than an outside diameter of the formed barrel at any point of the barrel. The method also includes forming2020a plurality of flutes defined around and in the one-piece formed barrel between adjacent fins wherein an inside diameter of the flutes is equal to a minor diameter of the fins and less than an outside diameter of the formed barrel. The method additionally includes forming2030a plurality of cooling sections between a barrel collar and a muzzle end of the solid barrel, each cooling section having a plurality of fins having a major outer diameter and a minor inner diameter.

Notwithstanding specific embodiments of the invention have been described and illustrated, the invention is not to be limited to the specific forms or arrangements of parts so described and illustrated. The scope of the invention is to be defined by the claims and their equivalents.