Patent Publication Number: US-2005115128-A1

Title: Single loading enhancement device for firearm

Description:
DESCRIPTION OF RELATED ART  
      Firearms are a common part of our culture. They are used for a wide variety of purposes. Among the most popular uses is the recreational, sporting or competitive use of firearms. Organized or informal matches or competitions take place at virtually every firing range. Among the most popular of the organized competitions are the rifle matches. These matches often have strict rules to promote safety and parity among the competitors. Quite often within these matches, the rules require that the firearm be loaded with one cartridge at a time, i.e., singly, even if the firearm&#39;s magazine or clip is capable of holding more than one cartridge.  
      When competition rules require that cartridges be loaded singly, competitors must not load the firearm&#39;s magazine with more than one cartridge. At these stages of a competition, the competitors are given ample time to load their firearms and score their targets. Speed is not preferred over safety. The emphasis is on marksmanship; thus the rate of fire is not very important. The single loading requirement decreases the likelihood of a safety problem, such as a trigger failure on a self-loading firearm that permits the firearm to operate automatically.  
      Many firearms are very sensitive to cartridge alignment and positioning during the single-loading process. A misaligned or poorly positioned cartridge may cause the firearm to malfunction. These firearms, including many automatic, semiautomatic, and bolt action rifles, are meant to be fed from a magazine. The magazine provides the proper cartridge position and orientation for problem-free functioning, but some problems still exist. To load a single cartridge with the magazine in place, many times the shooter must place a cartridge inside the firearm through a small port, such as with an M-16 or AR-15 type of firearm. Also, use of a standard magazine requires that the shooter follow a particular routine. Often, when the shooter simply places or lays a cartridge on top of the magazine&#39;s follower, the cartridge is not properly aligned and will not load properly. In some situations this can be hazardous. As the bolt forces the cartridge forward, the tip of the bullet may strike the receiver of the barrel extension. In this situation, the bullet may be forced deeper into the cartridge, dramatically altering the overall length and decreasing the internal volume of the cartridge. Any decrease in internal volume increases the cartridge&#39;s internal pressure when it is fired. Excessive pressure may cause damage to the firearm and injury to the shooter. If the shooter is lucky, the excess pressure will only degrade the accuracy of that shot. Alternatively, the firearm&#39;s bolt may force the cartridge from its perch atop the magazine follower and out of the firearm completely. This happens when the cartridge is not precisely aligned with the bolt and chamber. If the shooter does not witness the event, he may proceed as if there is a cartridge in the chamber. When the shooter tries to fire the cartridge, nothing will happen. The shooter must treat the event as a potentially hazardous hangfire or misfire until the truth is discovered.  
      However, even if the loading process does not create a hazardous condition, the loss of or damage to a cartridge may affect the competitor&#39;s rhythm or routine. If the damaged cartridge fires, accuracy may suffer due to the damage. If the cartridge is missing, the shooter has wasted time. It forces the shooter to find the lost cartridge or to replace it with another. One way to avoid these issues is to latch each cartridge into a standard magazine before each shot, feeding the cartridge from the magazine. In such a case, the cartridge is held under spring pressure between the magazine&#39;s follower and the magazine&#39;s feed lips, the same way it occurs when the shooter loads more than one cartridge into a magazine. The cartridge is squeezed against the bottom of the feed lips by the follower, under spring pressure from the magazine spring. This process works properly only if the cartridge is not too long to fit into the magazine or to function properly as the top cartridge in a magazine. However, even if a cartridge can function properly from a magazine, the extra stress on the cartridge may damage it, reducing accuracy.  
      At least one attempt has been made to address the problem of properly single-loading magazine-fed firearms. The Sinclair International company and others made and sold a device that replaced a magazine&#39;s follower for AR-15 and M-16 type firearms. It required a “sacrificial” magazine to make it work. The sacrificial magazine was disassembled and the original follower was replaced. This solution created several problems. First, magazines are not inexpensive. Purchasing an expensive magazine to use as a shell is a waste of money and resources. Second, the follower replacement does not function totally reliably without a lot of fine-tuning for the intended firearm. The shooter had to tune the follower replacement for his individual rifle to try to achieve proper functioning. However, many firearms simply will not operate properly with these devices. With respect to self-loading firearms, such as semiautomatic rifles, this is a problem because the bolt catch may not actuate. This requires the shooter to operate the bolt catch manually, negating any time savings from the follower replacement.  
      Thus what is needed is a device that replaces the firearm&#39;s magazine to allow reliable single-loading of a cartridge into a magazine-fed firearm. The device should replace the original magazine, and permit proper functioning of the firearm without damaging the cartridges or degrading accuracy.  
     SUMMARY OF THE INVENTION  
      The device is a magazine replacement for a firearm, more specifically a single loading enhancement device (sled) for firearms. The sled allows reliable, proper feeding of a cartridge into a magazine-fed firearm when single loading is required. The sled replaces a magazine during single loading events. The sled is inserted into the firearm just as a normal magazine. It is held in place with the firearm&#39;s original magazine catch, and is released by normal operation of the firearm&#39;s magazine catch.  
      The shape of the sled and its guide channel guides the cartridge securely and properly into the firearm&#39;s chamber. If the firearm is so equipped, the sled actuates a bolt hold-open device. This allows ease of reloading for subsequent shots.  
      The sled solves at least two problems: reliable single feeding of rounds into a magazine fed firearm, and the reliable actuation of an existing hold-open device, or bolt catch, on the firearm.  
      Existing devices use an insert to replace the follower of the original magazines. This method is an ineffective compromise due to several factors, including: the shape of the existing magazines, the strength of the magazine&#39;s spring, and the mass of the insert. The combination of factors, together with the range of allowable manufacturing tolerances for each piece, frequently act together to cause binding of the insert within the magazine, failure to feed cartridges properly and failure to actuate the bolt catch.  
      The sled was developed by addressing each problem separately. There are two main problems to over come, reliable cartridge feeding, and proper operation of the bolt catch or hold-open device, if so equipped.  
      With regard to reliable cartridge feeding, the shape of the sled was created to orient the cartridge in the proper location, when installed in the firearm, to guide the cartridge into the chamber. The cartridge must be properly aligned along all three axes to enter the chamber properly. The shape of the top of the sled was designed with guide rails and a guide channel to guide the cartridge into the barrel&#39;s feed ramp or chamber without permitting the cartridge to become misaligned, to fall out the firearm or to be damaged. The operation of the firearm&#39;s bolt or bolt carrier cannot be interfered with. Each different type of firearm has a unique set of requirements, but all share the common problem and solution. This solved the cartridge-feeding problem.  
      The bolt catch or bolt hold-open device is typically a small lever, paddle, pin, plate or other device that interferes with the movement of the bolt and prevents the bolt from moving forward. The bolt catch is important only to self-loading firearms, such as semiautomatic and automatic rifles. On most firearms, it is actuated by the magazine&#39;s cartridge follower or by a dedicated actuator attached to the magazine. As the ammunition in the magazine is depleted, the follower rises up and moves the bolt catch into an interference position with the bolt. This stops bolt movement and holds the bolt open when the magazine is empty. The force required to operate the bolt catch is relatively small. The bolt catch simplifies the operation of the firearm. When a firearm has a bolt stop, particularly self-loading firearms, the sled incorporates a spring-loaded plunger, pin or other mechanism to actuate the bolt catch. Where a firearm has no bolt catch, the function of a sled for that firearm is focussed toward reliable feeding only.  
      Existing magazines were measured to create generally proper magazine replacements. These rough parts were milled and fitted to a firearm to establish ramp orientation dimensions for that firearm. Where there are moving parts, sufficient clearance was built in to prevent excessive interference. At that time, bolt catch actuator mechanisms were properly located and installed. The firearm&#39;s action was cycled by hand with inert cartridges, and then final testing was done with live cartridges to ensure proper functioning. The sled was then tested with a wide variety of similar firearms to ensure proper functioning. If the sled did not operate properly in all the firearms, further adjustments were made to remedy the malfunction.  
      Accordingly, it is a principal object of the invention to provide a device for flawless single-loading of a magazine-fed firearm.  
      It is another object of the invention to teach a device that actuates a firearm&#39;s existing bolt catch mechanism.  
      It is a further object of the invention to provide a device that enables the proper functioning of a firearm.  
      It is another object of the invention to teach a device that uses a firearm&#39;s original magazine retention and release system.  
      It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.  
      These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIGS. 1 and 2  are perspective views of a sled for an AR-15 or M-16 type firearm according to the present invention.  
       FIGS. 3 and 4  are perspective views of a sled for an AR-10 type firearm according to the present invention.  
       FIGS. 5 and 6  are perspective views of a sled for an SR-25 or SR/LR308 type firearm according to the present invention.  
       FIGS. 7 and 8  are perspective views of a sled for a AR-15 or M-16 type firearm that is modified to fire 0.22 caliber rimfire ammunition.  
       FIGS. 9 and 10  are perspective views of a sled for an FN-FAL type firearm according to the present invention.  
       FIGS. 11 and 12  are perspective views of a sled for a Tikka type firearm according to the present invention.  
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      The present invention is a single loading enhancement device (sled) for a firearm, comprising a body that generally matches the external dimensions of an original firearm magazine. The sled may be inserted into the firearm in place of the original magazine for flawless functioning when loading and firing single cartridges.  
       FIGS. 1 through 10  are perspective views of sleds for various self-loading firearms.  FIGS. 11 and 12  are perspective views of a sled for a bolt-action firearm.  
      The sled includes a body  10  where the external features of the body  10  are in the form of an original firearm magazine comprising a bottom end  12 , a front surface  14 , a rear surface  16 , a left side  18 , a right side  20  and a top end  22 . The various sides and ends of the body  10  may be featureless or may include contours or grooves to accommodate layout of a particular firearm and ensure proper fit and function. The top end  22  further includes a left guide rail  24 , a right guide rail  25  and a guide channel  26  for proper alignment and control of a cartridge during the chambering process. The pair of guide rails  24 ,  25  is integrally formed into the top end  22  of the body  10  and oriented approximately parallel to the sides  18 ,  20 . The guide rails  24 ,  25  start near the front surface  14  of the body  10  and extend along the top  22  toward the rear surface  16 . A guide channel  26  is between and defined by the guide rails  24 ,  25 . The guide channel  26  is set into the top end  22  of the body  10 , and the width and depth of the channel  26  is slightly larger than the radius of a firearm cartridge. The overall dimensions and orientation of the guide rails  24 ,  25  and guide channel  26  are formed to prevent mechanical interference with the firearm&#39;s action and any moving parts. There are several variations within this basic layout.  
      In one embodiment, the guide rails  24 ,  25  extend along the top end  22  of the sled from the front surface  14  to a position approximately half way between the front surface  14  and the rear surface  16  of the sled. To accompany the truncated guide rails  24 ,  25 , the guide channel  26  extends along the top  22  of the sled from the front surface  14  of the sled to a approximately position half way between the front surface  14  and the rear surface  16  of the sled. This is shown in  FIGS. 7 and 8 , where the firearm has been modified to fire a much shorter cartridge than originally designed. In this case, the .223 Remington cartridge and the appropriate barrel and chamber have been replaced with a barrel and chamber that accepts and fires .22 caliber rimfire ammunition. The rimfire cartridges require significantly less bolt travel to properly extract, eject and load the cartridges, and a rimfire cartridge occupies only a small fraction of the space at the top end  22  of the sled. Thus this firearm needs a sled that has guide rails  24 ,  25  and a guide channel  26  that occupy only a part of the top end  22  of the sled.  
      In another embodiment, the guide rails  24 ,  25  extend along the top  22  of the sled for substantially the entire distance from the front surface  14  of the body  10  to the rear surface  16  of the body  10 . To accompany these longer guide rails  24 ,  25 , the guide channel  26  extends along the top of the body  10  for substantially the entire distance from the front surface  14  of the body  10  to the rear surface  16  of the body  10 . This is shown in  FIGS. 1 through 6  and  9  through  12 , where the cartridge length is approximately the same as the length of the top end  22  of the sled.  
      In the preferred embodiment, the sled is machined from a single piece of material. Dehin® is favored because it can be machined, resists mechanical damage and also resists oil, grease, and cleaning chemicals. Wood, metal and other synthetic materials may also be used to construct a sled. Further, sleds may be made from multiple pieces and assembled to form a complete sled, as an alternative to machining a sled from a single piece of material.  
      The sled may further include a magazine catch slot  28  formed of machined into the body  10  of the sled. The magazine catch slot is typically located in the same place as the original firearm magazine, such as the front surface  14 , the rear surface  16  or a side wall  18 ,  20  of the body  10 . The magazine catch slot  28  enables the sled body  10  to be removably attached within a magazine well on the repeating firearm.  
      In another embodiment, the sled further comprises a bolt-catch activation mechanism incorporated into the rear surface  16  of the body  10 , where the bolt-catch activation mechanism accomplishes the same function as the bolt-catch activation mechanism found on the original magazine. The bolt catch actuator may be a spring-loaded pin, plunger, or lever incorporated into the sled body  10 . Two different kinds of bolt-catch mechanisms are show in the Figures.  FIGS. 1, 2 ,  7  and  8  show a bolt-catch activation mechanism with a spring-loaded plunger  30 . The plunger mechanism  30  is fixed into a recess near the junction of the top end  22  and the rear  16  of the body  10 . The plunger mechanism  30  is oriented vertically with the plunger pointing upward. The plunger is biased to an extended position by an internal spring so that the firearm&#39;s bolt catch mechanism is activated when the bolt travels far enough to the rear. This holds the firearm&#39;s bolt open after each shot is fired.  
       FIGS. 3 through 6 ,  9  and  10  show a bolt-catch activation mechanism with a sliding plate  32 . The sliding plate is spring-loaded, vertically-oriented and biased upward by the internal spring. The sliding plate mechanism  32  is fixed into the rear surface  16  of the body  10  in a position and location to properly operate the firearm&#39;s own bolt-catch mechanism to hold the bolt open after each shot.  
       FIGS. 11 and 12  show a sled without a bolt catch activation mechanism. Bolt-action firearms, such as the Tikka, Remington model 700 and Winchester model 70, are entirely manually operated. There is no operating spring or other mechanism to close or open the bolt. Thus, no bolt-catch or activator is required.  
      The external appearance of the sled is that of a firearm magazine. The top of the sled has guide rails  24 ,  25  and a guide channel  26  that is specially contoured to control a cartridge on its way into the chamber of a firearm. Numerous variations are appropriate depending upon the differences found in firearms designs. The biggest differences are found in the top ends  22  of the different sleds. For example,  FIGS. 1 and 2  show a sled for an M-16 and AR-15 firearm. The guide rails  24 ,  25  are generally symmetrical as is the guide channel  26 .  FIGS. 3-6  show sleds appropriate for use with AR-10 and SR/LR308 firearms. Here the guide rails  24 ,  25  and guide channel  26  are quite asymmetrical. The guide channel  26  is skewed to the left side of the top end  22  of the sled to ensure proper cartridge feeding in those firearms. The guide rails  24 ,  25  and guide channel  26  are precisely formed to provide the appropriate inclination and orientation to chamber a cartridge without damage, improving accuracy and dramatically reducing wear on expensive magazines.  
      It is to be understood that the present invention is not limited to the sole embodiments described above, but encompasses any and all embodiments within the scope of the following claims.  
      Part # Part Name 
       10  body      12  bottom      14  front      16  rear      18  left side      20  right side      22  top end      24  left guide rail      25  right guide rail      26  guide channel      28  magazine catch slot      30  spring-loaded plunger-type bolt-catch activator mechanism      32  sliding-plate-type bolt-catch activator mechanism      34       36       38       40       42       44