Manually-operated firearm with forward-moving barrel and automatic breech lock
GOVERNMENT INTEREST 
     The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates to manually-operated breech-loading firearms, and particularly to such firearms having a barrel that is moved forward after firing to open the breech at the rear of the barrel bore. Firearms of this type normally are provided with means for mechanically locking the barrel and breech block against any motion in closed position during firing, and such means must be released after firing to open the breech. 
     An object of the present invention is to eliminate the usual mechanical locking means, and provide a firearm with connecting means between the breech block, the barrel and the receiver that effectively lock the breech block, barrel and receiver together during firing and automatically release the barrel after firing to permit forward movement thereof to open the breech. 
     In accordance with the invention, the firearm comprises a stationary receiver or frame, a breech block movable in the receiver, a barrel slidably mounted for forward and rearward movement on the receiver and connected at its rear or breech end to the breech block in firing position, whereby forward movement of the barrel to open the breech during firing is prevented by the breech block connection and the firing reaction on the breech block, but the barrel is automatically released after firing so that it can be moved forward to open the breech. The barrel is automatically disconnected from the breech block during the first part of the forward motion thereof, after which the breech block is stopped and the barrel can be moved forward relative to the breech block to open the breech for reloading. A detent may be provided for holding the breech block in its forward position during reloading. 
     Reference is made to an application of George E. Cooksey, entitled &#34;Manually-Operated Firearm With Forward Sliding Barrel and Pivoted Breech Block&#34;, Ser. No. 543,100, filed Jan. 22, 1975, with the same assignee, on which some of the claims herein are readable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical longitudinal section view of a portion of a firearm embodying the present invention, taken on line 1--1 of FIG. 2, with the parts in firing position. 
     FIG. 2 is a transverse section view, taken on line 2--2 of FIG. 1, with the cartridge removed. 
     FIG. 3 is a transverse section view taken on line 3--3 of FIG. 2. 
     FIGS. 4 and 5 are views similar to FIG. 1, with the parts in two other positions. 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     FIGS. 1-3 show a forwardly-moving breech-loading barrel firearm 1 embodying the present invention. The firearm 1 comprises a receiver or frame 3 having an elongated, rectilinear, T-shaped cavity 5 extending from a rear abutment 7 forwardly to the extreme front end 9 thereof. A breech block 11, having side ribs 13 to form a T-shaped cross-section, is slidably mounted in cavity 5 for limited forward and rearward movement in receiver 3. The breech block 11 comprises a first section 15, which extends downward beyond the receiver 3 to back up a cartridge 17 in the breech end 19 of a barrel 21, and a forward-extending, barrel-locking second section 23 having a notch 25 forming a rearward-facing locking abutment 27. The barrel 21 is mounted for forward and rearward movement in the receiver by an apertured front lug 29 and a first transverse pin 31 which extends through lug 29 and a pair of straight, longitudinal first slots 33 in the receiver 3, and a rear lug 35 and a second transverse pin 37 which extends through lug 35 and a pair of second slots 39 in the receiver 3. Each slot 39 is made up of a short, straight, longitudinal section 41 and a long, straight, longitudinal section 43, connected by an inclined section 45. The rear lug 35 is longer than front lug 29 to provide a forward-facing locking abutment 47 at the upper end thereof. When the breech block 11 and barrel 21 are in their rearmost positions, as shown in FIG. 1, the pin 37 is in the short slot section 41 and the abutments 27 and 47 are interlocked, thus locking the breech block 11 and barrel 21 together, and the pin 31 is at the rear end of its slots 33. 
     When the firearm 1 is fired, as by a hammer (not shown), striking a firing pin 49 (FIG. 3), the cartridge 17 is fired, ejecting the projectile or bullet 17&#39; from the barrel. The rearward reaction exerted on the cartridge case and breech block 11 by the burning propellant prevents the locked barrel and breech block unit from being moved forward at or during firing. However, after firing, as soon as the firing reaction has subsided, the locked barrel and breech block unit can be moved forward manually to open the breech. As the barrel 21 is moved forward, the pin 37 rides in longitudinal slots 41 and keeps the abutments 27 and 47 interlocked. As pin 37 rides down the inclined slots 45, it moves the rear lug 35 downward as shown in FIG. 4, releasing abutment 47 from abutment 27. Just beyond the position shown in FIG. 5, the breech block 11 is stopped by the rear end of a stop strip 51 which is mounted, as by screws 53, in the cavity 5, as shown in FIG. 5. A spring-pressed detent ball 55 may be mounted in the breech block 11 to seat in a detent recess 57 in the receiver 3, for holding the breech block in this forward position during reloading. The barrel 21 is moved further to the position shown in FIG. 5, opening the breech to permit removal of the fired case and insertion of a new cartridge. The fired case may be extracted by a manual extractor 59, shown in FIGS. 2 and 3. After insertion of a new cartridge into the breech end 19, the barrel 21 is manually moved rearward to close the breech. When the barrel 21 engages the breech block section 15, it moves the breech block rearward, releasing detent 55, and the inclined slots 45 and pin 37 raise the barrel abutment 47 behind the breech block abutment 27, thus locking the barrel and breech block together. 
     The foregoing disclosure and drawings are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense. I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, because obvious modifications will occur to a person skilled in the art.