BRIEF DESCRIPTION OF THE DRAWINGS
The detailed description of the invention, contained herein below, may be better understood when accompanied by a brief description of the drawings, wherein:
FIG. 1 is a side plan view of a submachine gun of which the closed bolt system with trigger assembly of the present invention can be installed to convert said submachine gun from a fully automatic to a semi-automatic firing weapon;
FIG. 2 is a partial perspective view of a submachine gun trigger housing that can be used with the closed bolt system with trigger assembly of the present invention for making the gun a semi-auto carbine;
FIG. 3 is an exploded perspective view of the closed bolt system with trigger assembly of the present invention that can be used with a trigger housing from fully automatic submachine gun to convert said gun to a semi-auto firing carbine of which can not be converted back to a fully automatic firing weapon;
FIG. 4 is a cross-sectional view taken along lines 4-4 of FIG. 2 showing a plurality of inter-connected elements of the closed bolt system with trigger assembly of the present invention prior to a trigger being pulled, showing a hammer as being cocked;
FIG. 5 is a cross-sectional view taken along lines 4-4 of FIG. 2 showing the plurality of inter-connected elements of the closed bolt system with trigger assembly just as the trigger is being pulled and showing how a disconnector arm, a disconnector and a sear all operate to release the cocked hammer;
FIG. 6 is a cross-sectional view taken along lines 4-4 of FIG. 2 showing the plurality of inter-connected elements of the closed bolt system with trigger assembly as the released hammer is striking a firing pin of the bolt located inside the semi-auto receiver of a weapon in which my invention is employed;
FIG. 7 is a cross-sectional view taken along lines 4-4 of FIG. 2 showing the plurality of inter-connected elements of the closed bolt system with trigger assembly as the bolt is “blowing” backwards within the semi-auto receiver and acting upon said plurality of trigger assembly elements;
FIG. 8 is a cross-sectional view taken along lines 4-4 of FIG. 2 showing the plurality of inter-connected elements of the closed bolt system of the trigger assembly just as the bolt has reached its backwards limit and has momentarily stopped before being pushed forward by the recoil spring mounted behind said bolt, and said bolt having reached its backwards limit allowing a new cartridge to be stripped into the firing chamber from an attached magazine or drum;
FIG. 9 is a is a cross-sectional view taken along lines 4-4 of FIG. 2 showing the plurality of inter-connected elements of the closed bolt system with trigger assembly as the bolt is springing forwards, showing how the hammer remains cocked and prohibited from re-striking the firing pin;
FIG. 10 is a cross-sectional view taken along lines 4-4 of FIG. 2 showing how the plurality of inter-connected elements of the closed bolt system with trigger assembly return to a “ready to fire” position when the bolt has reached its forward limit;
FIG. 11 is a cross-sectional view taken along lines 4-4 of FIG. 2 showing how the trigger can be drawn off the sear by a safety cam for placing the gun in a safety mode (non-firing) or for disassembling the gun; and
FIG. 12 is a perspective view of the semi-auto receiver employed with the closed bolt system with trigger assembly of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, a submachine gun 10 is shown. Gun 10 has a butt stock 12, a receiver 14, a barrel 16, a trigger housing 18 and a magazine 20. Gun 10 is typical of the design that can receive a closed bolt system with trigger assembly of the present invention to be more fully discussed hereinafter. Although the closed bolt system with trigger assembly could be installed in many different styles of guns, in its preferred embodiment, it is used with a Thompson Submachine Gun. For example, the closed bolt system with trigger assembly of the present invention can be used with a fully automatic Class III Thompson Submachine Gun. In such arrangement, only the trigger housing 18, butt stock 12, the sights, the safety lever and the original 10½ inch barrel are used. And if the 10½ inch barrel is used, the owner must obtain a short barrel rifle permit from BATF. However, if the owner buys a 16 inch barrel, then the short barrel rifle permit is not necessary. Or, an owner can buy a de-milled original fully automatic Thompson that is just unregulated parts (i.e., shipped to consumer with no receiver) and install the closed bolt system with trigger assembly of the present invention.
Referring now to FIG. 3, the closed bolt system with trigger assembly 22 of the present invention used to convert a fully automatic firing submachine gun into a single firing (semi-auto) carbine is shown in an exploded view (receiver not shown—see FIG. 12). The parts of closed bolt system with trigger assembly 22 include a bolt 24 having a bolt handle 26, a bolt lug 27 (see FIG. 4) and a firing pin 28 tensioned by a firing pin spring 30; both firing pin 28 and firing pin spring 30 are inserted in an axial bore 32 formed through a block portion 34 of bolt 24. Also included is a semi-automatic receiver 238 (see FIG. 12) having a cavity 240 capable of inclosing bolt 24. It is important to note that to make the gun a semi-automatic carbine which is incapable of being converted back to a fully automatic weapon, cavity 240 must be of a size that will not accept a bolt from a fully automatic Thompson. Accordingly, in the preferred embodiment, cavity 240 of semi-auto receiver 238 is made to be one inch and semi-auto bolt 24 is made to be between 0.93 and 0.95 of one inch. And this therefore classifies the weapon as semi-auto according to BATF.
With continuing reference to FIG. 3, axial bore 32 has a constricted but open distal end 36 (see FIG. 4) and a threaded open proximal end 38. A threaded cap 40 screws over threaded open proximal end 38 after firing pin 28 and firing pin spring 30 are inserted in axial bore 32. Further, firing pin 28 has a tip portion 42 that has a smaller circumference than that of a body portion 44 thereof. Firing pin tip portion 42 inserts within constricted distal end 36 of axial bore 32 when firing pin 28 is inserted therein (see FIG. 4 again).
With continuing reference to FIG. 3, it is shown that closed bolt system with trigger assembly 22 also includes a recoil spring 46 positioned behind semi-auto bolt 24 for affecting backward and forward motion of semi-auto bolt 24 during a firing sequence. As spring guide 242 is positioned behind recoil spring 46 to prevent “wading-up” of spring 46 when it is tensioned. Both semi-auto bolt 24 and recoil spring 46 are surrounded by receiver 14 (not shown in FIG. 3, but see FIG. 12). Semi-auto bolt 24 is guided back and forth along a horizontal trigger housing plate 48 extending rearwardly from trigger housing 18. As shown in FIG. 1, semi-auto receiver 14 locks to horizontal trigger housing plate 48, trigger housing 18 as well as to barrel 16 at a front end. Butt stock 12 engages horizontal trigger housing plate 48.
Returning back to FIG. 3, closed bolt system with trigger assembly 22 further includes a trigger 50 positioned within a trigger housing cavity 52 formed in trigger housing 18 and having a finger engagement portion 54 (having a crescent moon-like shape) extending into a modified trigger area 56 of trigger housing 18 below trigger housing cavity 52. An upper portion 58 of trigger 50 rests within cavity 52 and is enclosed therein when trigger 50 is positioned in place. Trigger upper portion 58 has a first and second bore, 60 and 62 respectively, formed therein such that first bore 60 is positioned below and rearwardly of second bore 62 and is slightly offset to a right side thereof and such that a length of first bore 60 is shorter than that of second bore 62. Also, first bore 60 has a slightly smaller circumference than that of second bore 62. Further, trigger upper portion 58 has a convexed-shaped outwardly extending upper ledge portion 64 that includes a trigger spring 66 positioned in a trigger spring cavity 68 formed in a bottom side 70 of ledge portion 64 (see FIG. 4). Trigger upper portion 58 also includes a convexed-shaped rearwardly extending upper ledge portion 72, having a width that is approximately half that of a width of convexed-shaped outwardly extending upper ledge portion 64. A disconnector arm tension spring 74 is intermediately positioned a bottom side 76 of ledge portion 72 (see FIG. 4) and a disconnector arm support ledge 78 formed in trigger upper portion 58. A disconnector arm tension spring cavity 80 (see FIG. 4) is formed in ledge portion bottom side 76 for retaining tension spring 74 by friction therein.
With continuing reference to FIG. 3, it is shown that closed bolt system with trigger assembly 22 also includes a disconnector arm 82 and a disconnector 84 integrally attached at a common axis. An inwardly extending rod member 86 protrudes from a right side from said common axis and inserts within trigger upper portion first bore 60. Both disconnector arm 82 and disconnector 84 have crescent moon-like shapes but of slightly different styles. Disconnector arm 82 has a lower leg portion 88 that rests upon a top surface 90 of support ledge 78. A small nipple 92 protrudes upwardly at a distal end 94 of disconnector arm lower leg portion 88 and inserts within a bottom portion of tension spring 74 (see FIG. 4). As will be later discussed and illustrated, tension spring 74 resets disconnector arm 82 after trigger finger engagement portion 54 is released and is integral to prohibiting gun 10 from automatically firing more than one bullet for each pull of the trigger. Disconnector 84 rests above first bore 60 and works to disengage disconnector arm 82 from a sear (to be discussed hereinafter), also assisting in prohibiting gun 10 from automatically firing more than one round for each pull of the trigger. Disconnector 84 is acted upon by semi-auto bolt lug 27 when semi-auto bolt 24 is blown back and tensions disconnector arm 82 against tension spring 74 requiring it to be “reset” before firing another round.
Further to FIG. 3, trip 96 has a pair of downwardly depending opposed side skirts 98 inserting around side walls of trigger upper portion 58. Trip 96 also has a pair of axially aligned apertures 100 formed therethrough that align with trigger upper portion second bore 62. An outwardly extending flat shelf 102 protrudes from a front section 104 of trip 96 and fits within a channel 106 formed at a front end 107 of trigger housing cavity 52. Trip 96 allows a stick magazine empty lug (not shown) to raise shelf 102 for the purpose of holding back semi-auto bolt 24 after the last round has been fired.
Still further to FIG. 3, a sear 108 is provided and has a cylindrical middle portion 110 and an outwardly extending top finger member 112 and rearwardly extending bottom foot member 114. A central bore 116 is formed through sear middle portion 110 thereby intersecting finger member 112 and foot member 114. Finger member 112 has a smaller width than that of middle portion 110 and is offset to a left side of sear 108. Foot member 114 has a varying width that depends from a greater value to a lesser value from middle portion 110 rearwardly. At a distal end of foot member 114, an upstanding wall 118 is provided. Meanwhile, finger member 112 has a downwardly depending tip 120 at its distal end. Further, on a bottom side 122 of foot member 114 (see FIG. 4), a sear tension spring 124 inserts within a bottom bore 126 (also see FIG. 4) formed in trigger housing cavity 52.
With reference to FIGS. 3 and 4, sear 108 sits within trigger housing cavity 52 slightly behind trigger upper portion 58. Disconnector arm 82 and disconnector 84 have an aggregate width that is equal to that of trigger upper portion 58 and therefore sits flush within trigger upper portion 58 such that opposed outer walls of disconnector arm 82 and disconnector 84 are flush with the opposed side walls of trigger upper portion 58. Since the width of sear middle portion 110 is generally equal to that of trigger upper portion 58 and the width of sear finger member 112 is generally equal to that of disconnector arm 82, sear finger member 112 rests juxtaposed against an inner side wall 128 (see FIG. 3) of disconnector 84 and sear finger member tip 120 rests on top of an upper top wall 130 of disconnector arm 82.
With reference now just to FIG. 3, a vertically disposed bolt hold back pawl 132 is provided for positioning juxtaposed between a left side of sear 108 and an inner left wall of trigger housing cavity 58. Bolt hold back pawl 132 has an aperture 134 formed therethough which axially aligns with sear central bore 116.
With continuing reference to FIG. 3, trigger assembly 22 further includes a hammer 138 tensioned by a hammer spring 140. Hammer 138 has a cylindrical portion 142 disposed at a lower front end 144 and a generally c-shaped rearwardly extending striking portion 146 used to slam against firing pin 28 when released from its tensioned state. Hammer spring 140 has a cradle portion 154 for receiving hammer 138, a pair of cylindrical wrappings 152 disposed on opposing ends of hammer cylindrical portion 142 and a pair of support legs 148 extending rearwardly and resting upon the bottom surface of trigger housing cavity 58 at a back end 150 thereof. Referring to FIG. 4., hammer 138 also has a downwardly extending nipple 156 disposed underneath cylindrical portion 142 and slightly offset to a rear portion for engaging sear foot member upstanding wall 118. This engagement is what “cocks” the hammer into a “ready fire” position. As will be further described below, disengagement of this contact (see FIGS. 5 and 6) will release hammer 138 and allow it to strike firing pin 28 which in turn fires a round.
All of the aforementioned parts that go into trigger housing assembly 18 are held in place by a series of levers, rods and cams. In particular, bolt hold back pawl 132 and sear 108 are secured by a rocker pivot 158 having a rod portion 162 for inserting through a rocker pivot aperture 160 (see FIG. 4) formed on the left side of gun 10 and through both bolt hold back pawl aperture 134 and sear central bore 116, which are all axially aligned, as shown in FIG. 3. It is noted that in converting a Thompson Submachine Gun, one can utilize the existing rocker pivot and aperture of such gun, eliminating any need to make modifications to trigger housing 18 except to provide for a small channel in trigger housing cavity back end 150 and to provide bottom bore 126 for receiving sear tension spring 124. Of course, since gun 10 is being converted to semi-auto, rocker pivot 158 will no longer select between different firing modes but instead acts as a cam when rotated back to hold semi-auto bolt 24 back. Rocker pivot 158 further includes a notched tip 164 formed in a distal end for protruding from an opposed aperture 166 formed in a right side of trigger housing 18.
With continuing reference to FIG. 3, a pivot plate member 168 having first and second inwardly extending posts, 170 and 172 respectively, mounts juxtaposed a right side of trigger housing 18. First inwardly extending post 170 inserts through a first right side aperture 174 formed in the right side of trigger housing 18 securing trip 96 and trigger 50 by intersecting both side skirt apertures 100 of trip 96 and second bore 62 of trigger upper portion 58. A distal end of first inwardly extending post 170 protrudes through a first left side aperture 176 (see FIGS. 1 and 2) formed in the left side of trigger housing 18. Second inwardly extending post 172 inserts through a second right side aperture 178 formed in the right side of trigger housing 18 securing hammer 138 by intersecting a central bore 180 formed in hammer cylindrical portion 142. A distal end 182 of second inwardly extending post 172 is received by a cylindrical cup 184 positioned within a second left side aperture 186 formed in the left side of trigger housing 18. It is noted that in relation to a front and back end of gun 10, first inwardly extending post 170 sits forward of second inwardly extending post 172. Further, both trigger housing first right and left side apertures, 174 and 176 respectively, are located forward, respectively, of both trigger housing second right and left side apertures, 178 and 186 respectively.
Still referring to FIG. 3, it is shown that pivot plate 168 has a generally oblong shape, a cutout portion 188 and a rearwardly extending finger 190 having a knuckled tip portion 192. When rocker pivot 158 is inserted into through aperture 158 to secure bolt hold back pawl 132 and sear 108, rod portion notch 164 protrudes through opposed aperture 166 and engages pivot plate 168 along finger 190. This assists in retaining pivot plate 168 flush against the right side of trigger housing 18.
With continuing to FIG. 3, a safety lever 194 is provided for locking hammer 138 when it is in a “cocked” (ready to fire) position. Safety lever 194 inserts through a left rear aperture 196 formed in the left side of trigger housing 18 proximal to the back end of gun 10 nearest to butt stock 12 and protruding out of a right rear aperture 198 (not shown) formed in the right side of trigger housing 18. Safety lever 194 includes an external knob 200, a rod portion 202 having a cutaway portion 204 and a distal tip having a circular groove 206 formed therein engaging knuckled tip 192 when the safety lever rod portion distal tip extends through right rear aperture 198. Groove 206 engaging knuckled tip 192 also assists in securing pivot plate 168 flush against the right side of trigger housing 18.
Referring now to FIGS. 4, 6 and 10, it is shown that safety lever 194 can be placed in two distinct states. A first state allows hammer 138 to release when trigger 50 is engaged and is therefore considered “ready-fire” (see FIG. 4 and 6). In a second state, hammer 138 is locked by rotating safety lever 194 to the rear which places gun 10 in “safe”, prohibiting the firing of a round (see FIG. 10). The solid part of rod portion 202 acts as a cam 208 and draws down hammer 138 off of sear 108 by pushing on a back area 209 behind c-shaped striking portion 146 of hammer 138.
As previously mentioned, closed bolt system with trigger assembly 22 can be installed into a fully automatic submachine gun for converting it to a semi-automatic firing carbine. By doing so, closed bolt system with trigger assembly 22 permits the firing of a single round for each pull of the trigger and prohibits a fully automatic firing mode. In the preferred embodiment, closed bolt system with trigger assembly 22 is used to convert a blowback, open bolt type weapon, such as a Thompson Submachine gun to a semi-auto carbine.
Referring to FIG. 4, closed bolt system with trigger assembly 22 is installed in a blowback style firearm. As shown, hammer 138 is in a “ready fire” position also known as being cocked. As such, as can be appreciated, trigger spring 66, disconnector arm tension spring 74 and sear tension spring 124 are all in their respective relaxed states. Further, downwardly depending tip 120 of sear finger member 112 is in contact with disconnector arm upper top wall 130. Further, disconnector arm 82 rests upon trigger upper portion disconnector arm support ledge 78. Still further, downwardly extending nipple 156 of hammer 138 is in contact (engaging) upwardly standing wall 118 of sear 108. This engagement prohibits hammer 138 from releasing from its tensioned state with hammer spring 140. As further shown, cam 208 is not engaging hammer 138, therefore gun 10 is not in a safety mode. Gun 10 is placed in this “ready fire” position by first placing a loaded magazine (not shown in FIG. 4) into a magazine receptacle. Then, bolt 24 is drawn back by hand by pulling on bolt handle 26 against recoil spring 46. Since an open bolt system is used in the preferred embodiment, a cartridge is stripped from the magazine and loaded into the chamber. The drawing back of bolt 24 also pushes down hammer 138 and acts upon disconnector 84 (to be discussed in further detail hereinafter) to place all parts into their respective depicted positions shown in FIG. 4.
FIG. 5 illustrates what occurs when the trigger is pulled. First, trigger finger engagement portion 56 is pulled backwards by a person's finger in the direction of arrow 212. This causes trigger upper portion 58 to tension trigger spring 66 and to rotate, counter-clockwise, about first inward extending post 170 as shown by arrow 214. This in turn pushes disconnector arm 82 upwards thereby causing upper top wall 130 to push up on sear downwardly depending tip 120. This action causes sear 108 to tension sear spring 124 by rotating, clockwise, about selector rocker pivot rod portion 162, as shown by arrow 216, further disengaging sear foot member upstanding wall 118 from downwardly depending nipple 156 of hammer 138.
Referring to FIG. 6, hammer 138 is released from its tensioned state by trigger spring 140 and rotates, counter-clockwise, about second inward extending post 172 of pivot plate 168, as shown by arrow 218. Hammer 138 strikes firing pin 28 causing firing pin tip 42 to protrude out of open distal end 36 of axial bore 32 making contact with a primer of a cartridge (not shown) and firing a round.
Referring now to FIG. 7, the result of the cartridge exploding causes the release of rapidly expanding gases that first pushes the bullet out of the front of the barrel. Bolt 24 “blows back”, against recoil spring 46, also due to the expanding gases inside of the chamber, but at a slower rate than that of the bullet exiting the barrel due to a great differential in inertia therebetween. As bolt 24 blows back, in a direction indicated by arrow 222, it acts upon hammer 138 by pushing it down thereby and rotating it, clockwise, about second inward extending post 172, as shown by arrow 224. At about the same time, bolt lug 27 acts upon disconnector 84 by pushing it down and rotating both disconnector 84 and disconnector arm 82, clockwise, about inwardly extending rod member 86 and tensioning disconnector arm 82 against disconnector arm tension spring 74 and also disengaging disconnector upper top wall 130 from sear downwardly depending tip 120. It is noted that at this moment in time, disconnector arm 82 is slightly lifted up from trigger upper portion disconnector arm support ledge 78.
FIG. 8 illustrates a moment in time where bolt 24 has reached its backward limit but has not yet begun to spring back forward. At his moment, disconnector arm 82 has been tensioned against disconnector arm tension spring 74 due to disconnector 84 being passed over by bolt lug 27. Further, hammer 138 remains tensioned against hammer tension spring 140 due to the position of bolt 24 applying pressure downward thereupon. However, sear 108 is allowed to rotate, counter-clockwise, about selector switch rod portion 162, as shown by arrow 228, since sear finger downwardly depending tip 120 is disengaged from disconnector arm upper top wall 130. Sear 108 rotation is affected by sear spring 124 releasing its tensioned state. As a result, sear foot member upstanding wall 118 re-engages hammer downwardly depending nipple 156 and “re-cocks” hammer 138 to ready fire.
Referring to FIG. 9, bolt 24 moves forward in a direction illustrated by arrow 230, due to recoil spring 46 releasing its tensioned state. However, hammer 138 is prohibited from re-striking firing pin 28 at this time due to the nipple 156—upstanding wall 118 engagement. Hammer 138 is re-tensioned, however, by hammer spring 140 and is considered “cocked.”
Referring to FIG. 10, pressure upon trigger finger engagement portion 54 is released allowing it to move forward in a direction indicated by arrow 232. In doing such, trigger upper portion 58 is released from its tensioned state causing both trigger spring 66 and disconnector arm tension spring 74 to relax. This causes disconnector arm 82 and disconnector 84 to rotate, counter-clockwise, about its axis (rod 86), as shown by arrow 234. As disconnector arm 82 rotates, it “resets” by engaging disconnector arm upper top wall 130 with sear downwardly depending tip 120. Now, gun 10 is ready to fire again upon the re-pulling of the trigger. If trigger 50 is not let go, then this “resetting” procedure can not occur and accordingly prohibits sear 108 from disengaging with hammer 138. However, it should be appreciated that the entire firing process, one pull of the trigger and then its release can still happen very quickly. In fact, everything that happens as described from FIGS. 5-10 can occur within one second. But under no circumstances, can a second round be fired without first releasing trigger 50 and allowing the “reset” of disconnector arm 82 with sear 108.
Referring to FIG. 11, a safety cam 208 is provided. Cam 208 is a part of rod 202 of safety lever 194. In ready fire (FIGS. 4-10), lever 194 is rotated such that cam 208 does not interfere with the movement of hammer 138. However, in the safety mode of FIG. 11, cam 208 rotates, counter-clockwise, as indicated by arrow 236, and engages a back side 209 of hammer 138. This action draws hammer 138 down upon trigger housing cavity back end 150 and separates hammer downwardly depending nipple 156 from sear upstanding wall 118. In the safety mode, trigger 138 can not strike firing pin 28. Further, in the safety mode, gun 10 can be disassembled.
Referring to FIG. 12, semi-auto receiver 238 is shown and has, in a preferred embodiment, a cavity 240 having a width of one inch. This accommodates semi-auto bolt 24 and prohibits a fully automatic bolt from being used therewith. In the preferred embodiment, semi-auto bolt 24 is between 0.93 to 0.95 inches.
Equivalent elements can be substituted for ones set forth herein to achieve the same results in the same way and in the same manner.
Patent Application
20070266845
