Abstract:
A firearm comprising a frame, a barrel joined to the frame, and a cartridge magazine selectively joinable to the frame; at least one cartridge contained within the cartridge magazine with the cartridge having a casing and at least one projectile, the casing having a cartridge case flange at one end and a mouth on the opposite end; and mechanism for lifting in selective communication with the cartridge and the barrel, with the mechanism for lifting having a ramp that is located adjacent to the end of the cartridge at the cartridge case flange, where the ramp acts selectively on the flange and casing; an extractor rib and barrel rib cooperating to keep extractor locked during cartridge ignition and unlocked substantially after ignition.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Non-Provisional patent application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/063,099 filed Feb. 1, 2008, entitled “Firearm with Cartridge Pick-and-Place Mechanism” 
    
    
     FIELD OF INVENTION 
     The present invention relates to automatic breech-loading firearms, more specifically to cartridge feeding systems. 
     BACKGROUND OF INVENTION 
     Automatic and semi-automatic firearms require manipulation of the next cartridge. The manipulation normally occurs through springs applying a force against the cartridge. Opening the chamber to eject a shell or spent cartridge stores energy in the slide spring and the magazine spring to a point where the springs release to “kick” a fresh cartridge into place. This type of mechanism, which is found in most semi-automatic firearms, lacks a positive grip on the cartridge, and usually has a feeding ramp in front of the cartridge, leading to numerous cartridge handling errors made more acute as the springs degrade. 
     One of these errors is known as a “feed ramp jam”, where the bullet tip stops against the feeding ramp surface, preventing the bolt from fully reaching battery position. Self-defense bullets, such as hollow-points are more prone to feed ramp jams due to their sharp corners on the tip. 
     Another error is incurred when the cartridge gets ahead of the extractor so that the slide will not fully go into battery. 
     Another error is known as “rim-lock”, where cartridge rims catch on each other in the magazine, which stops the slide from reaching its battery position. 
     Yet another error, known as “failure to extract”, is where the spent case remains in the chamber after ignition. It can be caused by percussion gases making the extractor lose its grip on the cartridge. 
     Another drawback of traditional feed systems is that they leave little room for the barrel. Short barrels do not provide enough burn time for propellant inside of the barrel, so instead the propellant burns on the outside, significantly increasing muzzle flash and noise. Short barrels also reduce bullet energy. 
     The most common cartridge feeding system is depicted in Hiram Maxim&#39;s 1885 U.S. Pat. No. 317,162, where positive control of the cartridge is not exercised. 
     Past examples of controlled or “positive” cartridge manipulation include U.S. Pat. No. 395,791 to Hiram S. Maxim dated Jan. 8, 1889. However, its design was bulky and not a practical solution for smaller weapons such as pistols. 
     Another example is GB Pat. No. 25,656 dated Sep. 27, 1906 to Mars Automatic Pistol Syndicate discloses a “pull-back”-style mechanism in a pistol. However, the gun&#39;s feed mechanism did not positively control the cartridge at all times, nor did it have means of arresting or trapping the upward motion of the cartridge to prevent feed failures. 
     Blow-forward feeding systems maximized barrel length, but never implemented positive cartridge manipulation. One example is U.S. Pat. No. 580,935 to C. J. Ehbets on Apr. 20, 1897. 
     Rotating barrel weapons have not taken advantage of the barrel rotation to lock the extractor closed during ignition. One example of a rotating barrel gun without extractor-locking is found in U.S. Pat. No. 4,984,504 to Pier G. Beretta on Jan. 15, 1991. 
     What is needed is a compact cartridge feeding system that eliminates the need for the front feed ramp of traditional cartridge feeding systems, and benefits from the positive nature of rearward-feeding systems that grasp a cartridge from the magazine, controls its motion at all times, and does not release it until during ejection from the firearm. What is also needed is a feeding mechanism that maximizes barrel length. What is additionally needed is an extractor that locks against the cartridge rim during ignition. 
     SUMMARY OF INVENTION 
     Considered broadly, firearms according to the invention are of the semi-automatic or fully-automatic type and include a frame, a barrel joined to the frame, a cartridge magazine selectively joinable to the frame, at least one cartridge contained within the cartridge magazine, with the cartridge having a casing and at least one projectile, the casing having a cartridge case flange at one end and a mouth on the opposite end; and a mechanism for lifting in selective communication with the cartridge and the barrel. The mechanism for lifting has a ramp that is located adjacent to the end of the cartridge at the cartridge case flange, where the ramp acts selectively on the flange and casing; an extractor rib and a barrel rib cooperating to keep extractor locked during cartridge ignition and unlocked substantially after ignition. This combination provides positive control of the cartridge from the extraction out of the magazine to the ejection of the fired case. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
       The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. 
         FIG. 1  is a cross section of the firearm taken along the middle, showing all major parts. 
         FIG. 2  shows a single-stack magazine being loaded from the rear. 
         FIG. 3  is a cross section of a single column magazine with a cartridge inside 
         FIG. 4  show the pair of tongs separated and laid flat 
         FIG. 5  shows the pair of tongs holding a cartridge 
         FIG. 6  shows the underside of the slide with a cartridge being held in the breech area 
         FIG. 7  shows two isometric views of the lifting mechanism 
         FIG. 8  is an isometric view of the coupler link assembly 
         FIG. 9  shows a retracted and partially extended view of the lifting mechanism Relative link lengths are also shown. The example is used for 9 mm ammunition 
         FIG. 10A-E  are cross sections through the centerline of the firearm in the feed mechanism area. Each figure represents a different stage of slide motion 
         FIG. 10A  shows the slide in the battery position with a cartridge in the chamber and one in the magazine being gripped by the tongs 
         FIG. 10B  shows the slide part way back with the cartridge riding over the ramp and the spent case touching the cartridge 
         FIG. 10C  shows the slide further back with the spent case ejected and cartridge lifting being initiated 
         FIG. 10D  shows he slide fully back with a cartridge being trapped in topmost position 
         FIG. 10E  shows the slide almost fully forward with a fresh cartridge mostly in the chamber and the tongs starting to engage the next cartridge in the magazine 
         FIG. 11  shows the spent case starting ejection, the cartridge below rising, and the ejector being cammed out of its way 
         FIGS. 12A-B  are horizontal cross-sections looking down at the gun through the top of the slide 
         FIG. 12A  shows the ejector in the active position 
         FIG. 12B  shows the ejector being cammed out of the way of a rising cartridge 
         FIG. 13  shows features on the barrel and ejector that allow for ejector locking 
         FIG. 14A  shows the barrel and ejector locked in battery position 
         FIG. 14B  shows the slide somewhat back with the ejector unlocked from the barrel 
         FIG. 15A  shows the overall view of a double-column magazine 
         FIG. 15B  shows a vertical cross section of a double-column magazine 
         FIG. 15C  shows a horizontal cross section and detail view of cartridge locating features 
         FIG. 16  shows a proposed single-column magazine that contains and locates bottle necked cartridges 
     
    
    
     DETAILED DESCRIPTION 
     Basic Components 
     The invention is a gun or firearm  20  comprised of four basic components: a frame  22 , a sliding bolt assembly  23 , a lifting mechanism  45 , and a magazine  30  to contain a column of cartridges  38  (see  FIG. 1 ). The frame provides mounting for these three assemblies. 
     The lifting mechanism  45  ( FIGS. 1 &amp; 7 ) is located directly behind the magazine  30 , both of which are substantially below the sliding bolt assembly  23 . The cartridge is trapped in front of the breech face  25  when the sliding bolt assembly is in the rearward position. 
     Sliding Bolt Assembly 
     The sliding bolt assembly  23  is movable from a battery position ( FIG. 10A ) to a rearward position ( FIG. 10D ) relative to the frame  22 , the magazine  30 , and the lifting mechanism  45 , and contains such standard components as the firing pin  58  ( FIG. 1 ) and its return spring  60 , barrel  26 , slide return spring  27 . Unique to the invention is the combination of the slide or sliding bolt  24  and insert block or secondary block  28  with a feeding extractor or tongs  40 , 42 . 
     The sliding bolt  24  contains two recesses,  28 E&amp; 24 B that act as vertical stops for the cartridge  38  being biased upwardly by the lifting mechanism  45 : one at the breech face  25 , consisting of a first concave surface  28 E facing downward (see  FIG. 1  and  FIG. 10D ) and one forward of the breech face  25 , a second concave surface  24 B also facing downward. The first concave surface  28 E protrudes from the breech face  25  and serves as a vertical stop for the cartridge case flange  38 A. The second concave surface  24 B is a groove that is normally occupied by the barrel when the sliding bolt is in battery position. This groove limits the vertical and horizontal travel of the forward portion of the cartridge  38 . The extractor  52  ( FIG. 11 ) is mounted to enable it to pivot in the sliding bolt  24  ( FIG. 6  and  FIG. 14A ) with a biasing spring diametrically opposing the grip slot  28 C in the insert block  28 , allowing the cartridge  38  to be captured in between. It is important to note that the grip slot  28 C does not capture the cartridge case flange completely, as has been done in pull-back style machine guns. The grip slot  28 C has a lead-out chamfer (shown adjacent to  28 C in  FIG. 6 ), which allows the cartridge case flange  38 A to slip out, and the cartridge case  38 C to swing out, when impacted by the ejector  54 . In other words, the grip slot  28 C does not have a positive grip on the case flange  38 A. 
     The secondary block  28  is mounted into the underside of the sliding bolt  24  via a flexible pin  32  ( FIG. 10A ) crossing through both parts in a direction perpendicular to the slide travel direction. The secondary block  28  has a hook or abutment  28 A ( FIG. 6  and  FIG. 10C ), which is used to actuate the lifting mechanism  45 , a cam-forward face  28 D ( FIG. 10D ) to force the lifting mechanism  45  back down, and a transverse pivot hole  29  to accept the tong pivot pin  56  ( FIG. 4  and  FIG. 5 ), which attaches the left hand tong  42  and right hand tong  40  to the insert block  28  ( FIG. 6 ). The pivot hole  29  in each tong is shaped to not only allow rotation about its pivot pin axis, but to also allow the tongs to open and close. Each tong  40 ,  42  has a lead-in or beveled surface  40 C &amp;  42 C that spread the tongs  40 ,  42  open while engaging a cartridge from the rear. Each tong has a mating feature, such as the right tong lug  40 E and the left tong slot  42 D which combined with the pivot pin  56  keeps the tongs parallel to each other, although the lug  40 E and the slot  42 D can be reversed or a pin crossing through both tongs could be used instead. Each tong  40 ,  42  has a gripping edge  40 A,  42 A that engages with the cartridge case flange  38 A for positive rearward draw. The tong gripping edges  40 A,  42 A are biased towards each other via the tong spring  68  which uses the tong pivot pin  56  as a fulcrum. Each tong also has a chamfered lower inlet  40 D that allows a case flange  38 A to enter from below during magazine insertion. Each tong has a curved cam groove  40 B &amp;  42 B underneath ( FIG. 4  and  FIG. 10E ) that cooperates with the lifting mechanism  45  for downward tong biasing during the return stroke of the sliding bolt assembly  23 . 
     Lifting Mechanism 
     The lifting mechanism  45  is a mechanism that swings from a lower position to an upper position ( FIG. 9 ). It is comprised of a flip link or first link  50  a lower link or second link  48 , a coupler link or third link  47  ( FIG. 8 ), and a torsion spring  49  to bias the mechanism in the lower position ( FIG. 10A ). The first link  50  and second link  48  are pivotably attached to the frame ( FIG. 10A ). The third link  47  connects the first link  50  to the second link  48  via pivot pins on either end. The third link  47 , in the illustrated example is comprised of a link body  51  and a ramp  46  ( FIG. 8 ). The third link could be configured whereby the ramp  46  and coupler link  51  are as one piece. The link body  51  serves as a mounting base for the ramp  46 , which curls around a cross pin  46 B that is attached to the link body  51 . A forward slope  46 A is also formed into the ramp  46  to guide a cartridge  38  upward and rearward from the magazine  30  (see also  FIG. 10B ). The ramp  46  is supported on both ends by the link body  51  and has an unsupported free span between both ends that is able to flex downward while lifting a cartridge. The rearmost end of the ramp  46  is cantilevered so that it can be lifted by the flip link nose or second cam surface  50 B ( FIG. 10D ). The first cam surface  50 A is specially-shaped to receive input from the rearward-traveling secondary block abutment  28 A to provide actuation of the lifting mechanism. The shape of the first cam surface  50 A cooperates with the shape of the abutment  28 A to produce lifting velocity and acceleration that is less than the sliding bolt assembly  23  velocity and acceleration, such that cartridge  38  contact with the ramp  46  top surface is substantially maintained throughout the lift. A cam back or third cam surface  50 C ( FIG. 10E ) on the first link  50  engages the tong grooves  40 B &amp;  42 B to reset the tongs  40  &amp;  42  in the down position when the sliding bolt assembly  23  is fully forward. 
     Ejector 
     The ejector or ejector lever  54  ( FIG. 12A ,  12 B) is mounted to the frame  22  in a location that impacts the cartridge case flange  38 A below its centerline, which is where the ejector  54  passes through the ejector slot  28 B. Slightly above the barrel  26  centerline, the cartridge is contained by the grip slot  28 C ( FIG. 6 ), which is opposed by the spring-loaded extractor  52  ( FIG. 6 ). 
     The ejector  54  ( FIG. 10C  and  FIG. 12A ,  12 B) hinges at pivot  59  relative to the frame  22  and is biased in a direction that forces collision with the spent case  38 C. 
     The spring member  66  is mounted into the frame  22  and acts upon the ejector lever  54  to force it against the ejector stop  57 , also built into the frame  22 . The ejector tail  55  is integral with the ejector lever  54  and cooperates with a cam surface  24 A on the sliding bolt  24  to drive the ejector lever  54  in a counterclockwise direction (viewed from the top) when avoiding a rising cartridge  38 . 
     Cartridge Magazine 
     The cartridge magazine or magazine assembly  30  (See  FIG. 2  &amp;  FIG. 3 ), which can be a traditional box-style, encloses a single column of cartridges  38  and is partially contained within the frame  22  when installed. The magazine  30  is comprised of a body or tubular structure  30 A, a spring  36 , a floor plate  37 , lips  30 C, and a rib  30 B that references the cartridge case mouth  38 B, preventing forward axial motion of cartridges contained within the tubular structure  30 A. The rib  30 B should extend entirely along the column of cartridges  38  so that upwardly flowing cartridges are not interrupted by changing surfaces. If the rib  30 B is not contiguous, another means of cartridge retention in the forward direction, such as engaging in cartridge case flanges  38 A, must be maintained until the cartridge  38  encounters the rib or ribs  30 B. In such a design, the top ribs  30 B can be provided by an additional piece whose function would be to both contain the cartridge stack against the spring  36  and to prevent forward axial motion of the top cartridge  38 . 
     The tubular structure  30 A can be made from a single piece, but two pieces is preferred since the rib  30 B needs to maintain a reasonably square edge to guide the case mouth  38 B. Additionally, two-piece construction allows the rib  30 B component of the body  30 A to be made of a thicker material, making it dimensionally more stable and resistant to deformation. The spring  36  is rectangular in a substantially rectangular form and has a very short solid height so as to maximize cartridge space. The floor plate  37  is affixed to the bottom of the tubular structure  30 A to contain spring  36 . 
     Extractor Locking Components 
     The barrel  26  is vertically captured between two components: the sliding bolt  24  on top, and the unlock block  62  on the bottom, which is mounted to the frame  22  ( FIG. 1  &amp;  FIG. 13  &amp;  FIGS. 14A-14B ). The barrel  26  is comprised of a long cylindrical body with rotary breech-locking lugs  78 , a rotation lug  70  which cooperates with the rotation groove  72  in the unlock block  62 , and a barrel rib  74 , which cooperates with the extractor rib  76 . The unlock block  62  contains the rotation groove  72  that receives the barrel rotation lug  70 . The rotation groove  72  is comprised of a straight section that is parallel to the barrel, and a helical section that serves to cam the rotation lug  70  in the circumferential direction thereby rotating the barrel  26  so that its rotation lugs can unlock from the slide body or sliding bolt. 
     Operation 
     Magazine Loading Process 
     Unlike traditional cartridge feeding systems, cartridges  28  are loaded into the magazine  30  from the rear ( FIG. 2  &amp;  FIG. 3 ). With the bullet pointing forward, the first cartridge  38  is placed on top of the spring  36 , with a forward force to register the case mouth  38 B against the rib  30 B; the subsequent cartridges  38  are placed on top of each other while pushing each cartridge fully forward. 
     Similar to traditional feeding systems, the cartridge magazine  30  is inserted into the magazine well from the bottom of the frame and retained with a magazine release. 
     Magazine Extraction Process 
     There are two modes for the tongs  40  &amp;  42  to attach to uppermost cartridge  38  in magazine  30  ( FIG. 4  &amp;  FIG. 5  &amp;  FIG. 10A ). The first is the insertion of the magazine  30  into the frame  22  whereby the case flange  38 A of top cartridge enters the spring-loaded tongs  40  &amp;  42  via the lower inlet  40 D on each tong. The tongs  40  &amp;  42  spread apart as the case flange  38 A slides between them. The second mode of attachment is by the return of the sliding bolt assembly  23  ( FIG. 10E ). Since the lifting mechanism  45  has at this point returned to the lower position, the first link  50  is also in its lower position, allowing cam back  50 C to operate against the grooves in the tongs  40 B &amp;  42 B to pivot them down as the sliding bolt  24  moves forward. Lead-ins  40 C &amp;  42 C on the front of each tong  40  &amp;  42  will slide over the back of the case flange  38 A, forcing the tongs  40  &amp;  42  apart against the tong spring  68 , until the grip edges  40 A &amp;  42 A of the tongs  40  &amp;  42  have snapped over the case flange  38 A. Some tong over-travel, usually more than 0.015-inch, is required to guarantee complete snap-over. 
     Once the tongs  40  &amp;  42  are attached to the top cartridge  38  in the magazine  30 , and a fresh cartridge  38  is in the chamber, the gun  20  is ready to fire and feed a cartridge  38  at the same time ( FIG. 10A ). At the time of percussion, the sliding bolt assembly  23  begins rearward travel and insert block&#39;s  28  inertia resists motion, causing the flexible pin  32  to bend, allowing the insert block  28  and on-board tongs  40  &amp;  42  to momentarily remain in place. The flexible pin  32  then begins to spring back, allowing the insert block  28  to gradually catch up with the sliding bolt  24 , delaying and softening rearward acceleration of the cartridge  38  being gripped by the tongs  40  &amp;  42 , thus minimizing possible separation of bullet from cartridge case. Typically, the gap  64  between the slide and insert block should be 0.014-inch or more. A suitable material for the flexible pin would be a commercially available coiled roll pin in alloy steel or stainless steel. 
     Since cartridges are positively drawn from the magazine  30 , there is no need for a lower guiding surface inside the magazine, such as a magazine follower used in traditional magazines. Another feature of the magazine extraction process is the presentation angle  31  of the uppermost cartridge  38  ( FIG. 10A ). The key is to have the angle between the axis of the cartridge and the line defined by the cartridge gripping point and tong pivot to be a non-zero value, more preferably 3 degrees or more. That way, during percussion, the rearward acceleration of the cartridge  38  is softened by the fact that the cartridge  38  must straighten out its angle to zero degrees relative to the tongs  40  &amp;  42  before any significant rearward motion of the cartridge  38  can occur. 
     Due to the very high acceleration experienced by the sliding bolt assembly  23 , precaution must be taken in the design of the hammer  44 . The contact point between the hammer  44  and the insert block  28  must be kept as high in elevation as possible, to minimize the angular velocity of the hammer  44 , to prevent it from severely over-traveling and damaging the frame  22 . 
     Lifting Mechanism Sequence 
     As a cartridge  38  is drawn from the magazine  30 , it is presented to the lifting mechanism  45  which is at rest in its lowermost position. The cartridge  38  first encounters the forward slope  46 A on the ramp  46 , which steers the cartridge  38  in an upward direction toward the spent case  38 C being extracted from the chamber, which helps limit the vertical travel of the cartridge  38  as it slides along the top surface of the ramp  46  ( FIG. 10B ). For a short time, the cartridge  38  and spent case  38 C are substantially parallel to each other, until the secondary block abutment  28 A catches the first cam surface  50 A and begins the actuation of the lifting mechanism  45  ( FIG. 10C ). Since the sliding bolt  24  is normally moving very fast, the motion imparted to the lifting mechanism  45  is also very fast, and causes the cartridge  38  to rise abruptly. While moving upward, the ramp  46  can absorb some of the impact against the cartridge  38  by flexing downwardly. The rising of the cartridge  38  continues as the spent case  38 C strikes the ejector  54 . The spent case  38 C is also being affected by the cartridge  38  from below by being wedged away from the inboard side of the ejection area in a manner that amplifies the ejection velocity of the spent case  38 C. In other words, both the ejector  54  and the cartridge  38  are impacting the spent case  38 C simultaneously. 
     With the spent case  38 C fully clear of the breech area, the cartridge  38  continues upwardly, bringing along tongs  40  &amp;  42 , which are still attached to the cartridge  38 . The tongs  40  &amp;  42  cease pivoting motion when stopping against the underside of the secondary block  28  ( FIG. 10D ). With the lifting mechanism  45  continuing, the case flange  38 A will leave the tongs  40  &amp;  42 , spreading them apart against the tong spring  68 , and entering the cartridge breech face  25  for the cartridge  38  to be trapped. 
     While the lifting mechanism  45  link members can have different lengths, in practice it is desirable to have all four pivots of the lifting mechanism  45  form a parallelogram so that substantially parallel motion is imparted to the cartridge  38  during lift. In other words, the first link  50  and the second link  48  should be the same length, and the third link body  51  and the ground link (frame  22  pivot distance) should be the same length (see  FIG. 9 ). Non-parallel motion can cause the cartridge  38  to tilt in an undesirable way. 
     Ejector Bypass 
     The receding spent case  38 C is removed by striking the ejector lever  54 , but as the new cartridge  38  rises, the ejector  54  must now move out of the way to prevent it from contacting and diverting the cartridge  38  ( FIG. 11 ,  FIGS. 12A &amp; 12B ). This is done by a cam surface  24 A integral with the sliding bolt  24  acting upon the tail of the ejector lever  55 . This is timed so that just after the ejector has been struck by a spent case, it begins to rotate about its pivot  59  out of the way of a rising cartridge  38 . The ejector  54  maintains its out-of-the-way position ( FIG. 12B ) as the sliding bolt  24  finishes its rearward travel. 
     Cartridge Trap 
     As the cartridge  38  is lifted past the tongs  40  &amp;  42 , it enters into the breech face  25  region by sliding under the spring-loaded extractor  52 . Opposing the extractor spring on the opposite side of the breech face  25  is the grip slot  28 C ( FIG. 6 ), which receives the case flange  38 A and guides it during lift and when it arrives at top position. Just before the cartridge  38  reaches its top position, the sliding bolt assembly  23  has some remaining travel, but the lifting mechanism  45  is near toggle and will provide almost no additional lift. However the remaining slide  24  travel will impart additional rotation of the first cam surface  50 A to act upon the ramp  46  to provide additional lift to the cartridge  30 A ( FIG. 10D ). This lifting amplification allows the lifting mechanism  45  to be more compact. 
     The cartridge  38  reaches its upper travel limit when its case flange  38 A touches the flange stop or first concave surface  28 E and the case mouth  38 B area nests into the concave ceiling or second concave surface  24 B ( FIG. 10D ). Both concave surfaces are built in to the sliding bolt. Although the cartridge  38  has stopped, the flip link nose  50 A continues to rotate somewhat more, forcing the flexible tang  46  to bend against the case of the cartridge  38 , effectively clamping it against the concave upper surfaces  28 E and  24 B, completing the trapping process. 
     In practice, it is desirable to have the cartridge  38  lifted slightly above the barrel  26  axis when it is trapped. This reduces the tilt angle of the trapped cartridge  38  thus reducing stress on the extractor  52  and potential case flange  38 A cam-out from under the extractor  52 . 
     Cartridge Delivery to Chamber 
     Upon return of the slide  24  to battery, the cartridge  38  must now move down to become co-linear with the barrel  26  so that it can enter the chamber without requiring excessive lead-ins. This vertical offset should not exceed 0.070″ or the flat noses of some hollow point ammunition can catch on the chamber face. Typically, an offset of 0.035-0.060″ works best. For proper lead-in, a small chamfer of 0.015″-0.020″ on the chamber mouth is required. 
     Extractor Locking 
     When the sliding bolt  24  and barrel  26  are at rest in the battery position, the barrel rib  74  overlaps with the extractor rib  76  ( FIG. 13  &amp;  FIGS. 14A-14B ). After cartridge ignition, some gases escape rearward from the chamber, trying to force the extractor  52  to disengage with the case flange  38 A. However, the barrel rib  74  inhibits extractor pivoting until chamber gas pressure has significantly dropped. Recoil drives the barrel  26  and slide  24  rearward as the rotation lug  70  slides in the rotation groove  72  until it encounters the helical surface, which forces the barrel  26  to turn about its axis. By this time, the bullet has left the barrel  26  and chamber pressure has dropped to a level where extractor  52  blow-out can no longer occur. Barrel rotation continues until the extractor  52  is unlocked from the barrel  26 . Shortly thereafter the rotation also unlocks the barrel  26  from the slide  24 , allowing the barrel  26  to stop and the slide  24  to continue rearward. 
     Description and Operation of Alternative Embodiments 
     Dual-Column Magazine 
     A single-column magazine provides for a thinner gun for better concealment; however, a dual-column magazine results in greater capacity. In  FIG. 15  A,  15 B,  15 C and Detail AD we see a tubular structure  84  that is modified to include a wide section to contain a double column of cartridges  38  that converges into a single column. Although the invention relies on case-mouth location at the top position, which is provided by tightly spaced ribs  88 , it is not practical to guide two columns of cartridges this way. Instead, two rails  86 , formed by bending the edges of the tubular structure, engage the cannelures  39  to contain the alternating cartridges axially until the two columns merge into a single column, where case mouth location can be accomplished with the ribs. The spring  90  pre-loads the cartridge  38  stack and cannelures  39  against the opposing rails  86 . The floor plate  82  then caps off the bottom of the magazine. To guarantee that no forward axial movement of the cartridge is experienced during this transition, the rails  86  overlap with the ribs  88 . Lips  92  are also used on this design to oppose the magazine spring  90 . The floor plate  82  is attached the same way as a single-column magazine. Cartridges  38  are drawn from the rear by the tongs  40 ,  42 . 
     Bottle-Necked Cartridge Magazine 
     Bottle-necked cartridges  94  present an opportunity for simplification of the magazine design.  FIG. 16  shows the proposed magazine  98 . Instead of using contiguous ribs to guide the case mouth, angled folds  100  are used to register against the shoulder  96  of the bottlenecked cartridge  94 . All other features and functions would be identical to a case-mouth guided magazine. 
     Dual-Column Bottle-Necked Cartridge Magazine 
     This magazine would be analogous to the dual-column case mouth guided magazine shown in  FIG. 15C , except folds  100  would be used at the top instead of ribs  88 . Case flanges would be engaged by rails folded into the edge of the magazine body. 
     Single-Piece Sliding Bolt 
     The sliding bolt assembly has been defined as a three-element construction, relative to the invention. However, one element can be removed, the secondary block  28 , can be eliminated by incorporating its features into the slide itself. The tongs  40  &amp;  42  would then directly hinge to the slide. 
     Passive Ejector 
     A simpler extractor design would be to have the cartridge itself move the ejector lever out of the way. This would eliminate the need to machine a cam into the slide and would allow more lenient manufacturing tolerances of the related parts. The risk would be that the cartridge could be steered out of the weapon by the ejector spring force. Careful selection of an ejector spring and careful design of a lead-in on the underside of the ejector may overcome these issues. 
     CONCLUSION 
     It is thus evident that in the magazine cartridges are kept in forward alignment via case mouth registration. It is also evident that after a cartridge is drawn rearward from the magazine, it is guided, lifted, trapped and carried into the barrel chamber. It is additionally evident that the chamber extractor is locked during ignition and is automatically unlocked significantly after ignition. This arrangement affords reliable cartridge feeding, due to positive cartridge control at all times, and maximum kinetic energy of the bullet due to additional barrel length extending over the magazine. 
     While the above description contains numerous specificities, these should not be construed as limitations on the scope of the invention, but as exemplifications of the presently preferred embodiments thereof. Many other ramifications and variations are possible within the teachings of the invention, such as using the invention in rifles, machine guns and artillery. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, and not by the examples given.