Patent Publication Number: US-6212814-B1

Title: Receiver for firearm

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to apparatus for removing the magazine well from a semi-automatic weapon and providing the weapon with a single shot loading capability. 
     Semi-automatic firearms capable of firing a large number of rounds in a short period of time are readily available at affordable prices to the general public. Misuse of these rapid fire weapons, however, is of growing concern, particularly among law enforcement people. Most semi-automatic weapons can accept magazines holding twenty or more rounds, thus providing law breakers, terrorists and the like with unprecedented firepower. Attempts are presently being made to make the use of detachable magazines in association with this type of weapon illegal. 
     Many of these semi-automatic weapons are sold to sportsmen for hunting or target shooting purposes and accordingly there is no need for a large detachable magazine. No one to date, however, has attempted to remove the magazine well from a semi automatic weapon and allow for single shot operation of these potentially dangerous weapons. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to eliminate the magazine well of a semi-automatic weapon and make it impractical to reconvert the weapon to accept a a detachable magazine. 
     It is a further object of the present invention to eliminate the high capacity firepower of a semi-automatic weapon. 
     A still further object of the present invention is to eliminate magazine feeding of a semi-automatic weapon and replace it with manual reloading capability, without adversely effecting the automatic ejection operation of the weapon. 
     It is a further object of the present invention to provide a retrofit unit for an automatic weapon which converts the weapon to single shot use. 
     It is a further object of the present invention to provide an apparatus that can be easily installed into the receiver of an existing semi-automatic weapon that will eliminate the magazine well and limit the receiver to single shot use. 
     These and other objects of the present invention are attained by apparatus for retrofitting a semi-automatic weapon of the type equipped with a detachable magazine for bringing cartridges one at a time into the receiver of the weapon where the cartridges are fed into the barrel chamber by a bolt. The receiver of most automatic weapons includes an upper section that is a permanent part of the weapon and a lower section that is adapted to receive the magazine and which can be removed from the weapon. 
     One form of the invention involves a replacement for the removable lower receiver section of the weapon that converts the weapon from a semi-automatic weapon to a hand loaded single shot weapon suitable for use as a target rifle or for varmint hunting where a single shot is all that is generally required. A second form of the invention involves a magazine that can be permanently secured in the magazine of the weapon. The magazine is equipped with apparatus for converting the weapon from a magazine weapon to a single shot weapon. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of these and other objects of the present invention, reference will be made to the detailed description of the present invention which is to be read in association with the accompanying drawings, wherein: 
     FIG. 1 is a partial side elevation of a prior art automatic weapon illustrating a typical receiver capable of accepting a high capacity magazine; 
     FIG. 2 is a partial front elevation with portions broken away of a modified weapon similar to that shown in FIG. 1 embodying the teachings of the present invention; 
     FIG. 3 is a partial rear elevation of the modified weapon embodying the teachings of the present invention; 
     FIG. 4 is a partial perspective view of the modified weapon; 
     FIG. 5 is an enlarged perspective view of the bolt catch utilized in the present invention; and 
     FIG. 6 is a further embodiment of the present invention for modifying a semi-automatic weapon that is equipped with a detachable magazine. 
    
    
     DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, FIG. 1 illustrates a semi-automatic gas operated rifle, generally referenced  10 , which is well known in the art and which is further described in detail in U.S. Pat. No. 5,452,534 to Lambie, the disclosure of which is incorporated herein by reference. The rifle is arranged to fire from a closed bolt position and includes a receiver  10  that contains an upper section  13  and a lower section  15 . The lower receiver section is removably connected to the upper receiver section by a takedown pin  17  and a hinge pin  18 . Removal of the pins allows the entire lower receiver section to be completely separated from the remainder of the weapon. As will be described in greater detail below, the lower receiver section is easily replaced with a modified lower section embodying the teachings of the present invention and which will in no way effect the operation of the upper receiver section or the remainder of the weapon. 
     The prior art weapon includes a barrel  19  that is attached to the front of the upper receiver section by hinge pin  18  and which contains a chamber that opens to the receiver for accepting a cartridge fed from a magazine  20 . The cartridges contained in the magazine are fed in a well known manner one at a time from the magazine into the chamber by a slide bolt mechanism  23 . The weapon is fired by pulling the trigger  39  releasing a firing pin in the forward section of the bolt which, in turn, strikes the cartridges igniting the power contained therein propelling the bullet out of the barrel toward the target. After firing, the bolt is urged back from the firing position to a battery position and the spent cartridge shell is ejected from the weapon through the ejection port  25 . The bolt is then moved forward by a battery spring (not shown) stored within the stock  26  immediately behind the bolt. 
     A magazine well  30  is located in the forward part of the lower receiver and is adapted to slidably receive a magazine therein. To load the weapon, the magazine is moved upwardly into the well and is locked in place by a latching mechanism (not shown). Cartridges from the magazine are fed one at a time into the rifle breech where the bolt can pick up each cartridge and move it into the rifle barrel chamber. To remove the magazine from the well, a latch release found on the back side of the lower receiver is depressed which frees the magazine from the latching mechanism whereupon the magazine can be easily pulled from the well. 
     Most semi-automatic rifles of this type can accept magazines capable of storing more than twenty cartridges. This is far more than needed by a target shooter or varmint hunter. As noted above, semi-automatic weapons with this type of shell capacity are of little or no use to the average recreational shooter and in fact, pose a danger to the community if they find their way into the wrong hands. As will be explained below the present invention will allow potentially dangerous semi-automatic weapons to be quickly and easily modified so that they can be safely hand-loaded to fire one cartridge at a time and thus preserving the usefulness of the weapon while eliminating its potential danger. 
     The apparatus of the present invention will be explained in greater detail with reference to FIGS. 2-5 wherein like numbers are used to identify like parts as described above in regard to FIG.  1 . The lower receiver of the weapon is removed as noted above by removing pins  17  and  18  and replaced by lower receiver  40  which is illustrated in FIGS. 2 and 3 attached to the stock  26  of the weapon. The lower receiver  40  operates in the same manner as the part that it has replaced except it must be loaded one cartridge at a time and the magazine well has been eliminated. The replacement section contains a trigger  39  that is adapted to coact with the bolt  23  to fire a cartridge when the bolt is in a closed or firing position. 
     The lower receiver section  40  contains a forward nose section  41  having a flat upper surface  43 . A loading block  45  is secured to the upper surface by countersunk screws  46  so that various configured blocks can be mounted on the lower receiver to accommodate cartridges of differing sizes and shapes. The top of the block contains a concave cradle  47  that provides a seat for a cartridge. The loading block is formed of a lubricious material to permit a cartridge seated thereon to slide easily into the rifle chamber. The cradle is aligned with the central axis of the barrel and is inclined at a shallow angle as shown so that a cartridge mounted upon the block moves upwardly into the barrel chamber as the bolt is moved from the battery position to the firing position. 
     A bolt catch  50 , as best illustrated in FIG. 5, is mounted inside a well  51  formed in the back of the nose section of the lower receiver section. The catch includes a raised arm  53  having a hook like appendage  55  at its distal end which, as shown clearly in FIG. 4, is arranged to overlie the top of a plunger  57  that is slidably contained in a vertically disposed hole formed in the-lower receiver immediately behind the loading block. The bolt catch further includes a thumb actuated lever  58  that is pivotally mounted upon a pivot pin  59  (FIG.  3 ) on one side of the lower receiver as illustrated in FIG.  3 . The thumb lever is attached to the proximal end of the raised arm  53  by means of a connecting bar  60 . Depressing the thumb lever will cause the raised arm to rock downwardly against the plunger thereby depressing the plunger. 
     The bolt is provided with a groove that extends axially along the bottom of the bolt. In assembly, the top of the bolt catch  55  rides in the groove of the bolt. As illustrated in FIG. 2, the plunger  57  is slidably contained within a hole  61  formed in the lower receiver section and is urged upwardly by a spring  63  into biasing contact with the bar  60 . When the bolt is in a closed or firing position, the bolt catch is forced downwardly depressing the plunger against the spring action. Once a cartridge is fired, the bolt is forced back by the gases generated during firing against the holding action of the buffer spring until the top of the catch arm is cleared by the bolt whereupon the arm is raised by the plunger to prevent the bolt from moving forward. The spent shell is ejected through the ejection port during the retraction of the bolt in a manner that is well known in the art and need not be explained herein in further detail. 
     At this time, the ejection port is clear and a new cartridge can be loaded upon the loading block. The bolt is released by depressing the thumb lever which moves the catch arm downwardly a sufficient distance to allow the bolt to clear the catch. The released bolt is moved forward under the influence of the battery spring to engage the cartridge and drives it forward into the firing chamber of the rifle barrel thereby closing the chamber and placing the firing pin in a condition to fire the chambered round once the trigger is pulled back. 
     As should now be evident, the bolt catch and spring loaded plunger assembly has replaced the magazine finction of the automatic weapon. The present lower receiver section can be easily and rapidly retrofitted to most existing semi-automatic weapons or can be made a permanent part of the original equipment without any substantial increase in cost. Any attempt to alter a weapon not equipped with a magazine well would be extremely difficult and costly. 
     As best illustrated in FIG. 4, the lower receiver section is cast or otherwise formed so that the nose section  41  provides a relatively thin platform  42  upon which the loading block is supported. A thin vertical rib  48  is located beneath the platform which is joined integrally to the main body  49  of the lower receiver. Accordingly, the present nose section, because of its construction does not allow sufficient material to effectively remove the bolt latch and loading block and machine a magazine well needed to reconvert the weapon to a semiautomatic weapon. Preferably, the thickness of the platform should be one-half inch or less to make machining of this section difficult. 
     FIG. 6 illustrates a further embodiment of the present invention that is simpler and more cost effective than that described above. A dummy magazine  70  is created from an existing detachable magazine that has been stripped of its internal workings. The shell chamber  71  is filled with a fill material  73  such as a potting material that extends to the top rim of the magazine. A mounting block  45  of the type described above is removably mounted upon the top of the potting material by means of countersunk screws. A hole  61  is formed in the potting material immediately behind the mounting block and a spring  63  and a plunger  57  are slidably mounted in the hole. In assembly, the magazine is mounted within the magazine well of the weapon and is permanently secured in position by at least one rivet  75  that is passed through the side walls of the magazine well. Alternately the magazine can be permanently secured to the well using spot welds or the like formed within appropriate joint regions. When permanently mounted in the well, the plunger will be engaged by the bolt catch and the catch will operate in the manner explained above. 
     While this invention has been explained with reference to the structure disclosed herein, it is not confined to the details set forth and this invention is intended to cover any modifications and changes as may come within the scope of the following claims: