Firearm and caseless ammunition therefor

A firearm for firing caseless ammunition includes a barrel, a receiver, a bolt, and a firing pin. The bolt includes laterally open pockets for receiving a projectile and a separate propellant cartridge. The bolt carries an extractor to extract unspent projectiles. The bolt drives a locking collar to lock itself in forward position. The locking collar is unlocked by the recoil-action of the firing pin. The firing pin is driven by a spring biased hammer; the firing pin then drives the hammer by recoil action, causing the hammer to unlock the locking collar. A gas seal for the firing pin includes a deformable ring which is deformed by ignition gas pressure into sealing engagement with the firing pin. An anti-recoil muzzle at the discharge end of the barrel has a reaction surface thereof cleaned of combustion deposits by a plurality of bristles extending from the barrel. A propellant cartridge comprises a plurality of telescoping nitrocellulose jackets which form a propellant chamber and a primer compartment.

BACKGROUND AND OBJECTS 
The invention relates to improvements in firearms employing consumable, 
caseless ammunition. 
In the military, there is an interest in a form of ammunition for rifles 
and machine guns which does not require a metal case to house propellant. 
While there are a number of reasons for this interest, one compelling 
reason centers on the fact that the metal case comprises nearly 50% of the 
weight of each cartridge. Thus, for ammunition of like weight, a 
successful "caseless" format would afford a 2:1 firepower advantage over 
conventional weapons. 
Previous proposals in the caseless field are exemplified in U.S. Pat. No. 
3,474,560 issued to Ramsay on Oct. 28, 1969; No. 3,483,793 issued to 
Ramsay on Dec. 16, 1969; No. 3,641,692 issued to Wells on Feb. 15, 1972; 
Nos. 3,641,867, 3,828,676, and 3,990,347 issued Feb. 15, 1972, Aug. 13, 
1974, and Nov. 9, 1976, respectively, to the present inventor, and No. 
3,772,123 issued to Parisi on Mar. 27, 1973. The disclosures in U.S. Pat. 
Nos. 3,641,867, and 3,828,676, and 3,990,347 of this inventor are 
incorporated by reference herein as if set forth at length. 
Some prior proposals center around the employment, in conventional 
firearms, of a cartridge which is physically similar to the metal 
cartridge in that both the projectile and caseless propellant are packaged 
or fixed together. During loading, the cartridge would be engaged by a 
bolt and rammed forwardly into the firing position. In such an instance, 
the cartridge propellant must be exceedingly strong to withstand the 
forces encountered since the bolt, especially in the typical 
reciprocating-action automatic firearm, drives the cartridge against fixed 
chamber shoulders with considerable closing velocity. It has not proven 
feasible, however, to achieve the required degree of cartridge strength 
without interlacing the propellant with foreign materials which, upon 
firing, leave unacceptable high amounts of residue. 
Some proposals in the caseless field fail to provide for convenient 
extraction of an unspent projectile. That is, in the event of a misfire, 
substantial efforts and disassembly of the firearm may be necessary to 
remove the projectile and/or cartridge. 
Other problems in the caseless area involve complicated mechanisms for 
unlocking the bolt for recoil and recocking motion. It would be desirable 
to provide a simplified unlocking system. 
Although it has been heretofore proposed to harness the recoil motion of 
the firing pin to unlock the bolt, such proposals involve complex systems 
which do not enable the firing sequence to be initiated with the bolt in a 
forward, locked position. It would be desirable to avoid this problem as 
well as to provide a system where a spring activates the firing pin 
without being subjected to excessive stressing by firing pin recoil. 
It has been previously proposed to obturate around a firing pin in a manner 
requiring the formation of grooves in the pin to receive sealing rings. 
This, however, weakens the firing pin. 
Previous firearm designs render impracticable the use of replacement bolts. 
It would be desirable if bolts which have become fouled could be replaced 
conveniently in the field. 
Proposals have been made for providing anti-recoil muzzles at the discharge 
end of a barrel. The muzzle is to be provided with a reaction surface to 
be acted upon by ignition gases. However, the reaction surface may have a 
tendency to accumulate carbon deposits. Moreover, the surface of the 
barrel opposite the reaction surface is acted upon by the ignition gases 
to create recoil forces which, in effect, cancel-out the effectiveness of 
the anti-recoil muzzle. 
It is, therefore, an object of the present invention to eliminate problems 
such as these without unduly complicating firearm operation. 
It is a further object of the present invention to enable caseless 
ammunition to be effectively and efficiently employed in firearms. 
It is another object of the invention to minimize the shock to which 
caseless propellant is subjected in a firearm, while providing for the 
extraction of unspent propellant and projectile. 
It is another object of the invention to provide a bolt locking mechanism 
of such simplicity that it is practical to manufacture interchangeable or 
reserve bolts. 
Another objective is to provide a bolt which is removable for cleaning and 
maintenance purposes. 
It is a further object of the invention to provide a novel bolt locking 
mechanism in which the bolt locks itself and is unlocked by the recoil 
action of a firing pin. 
It is another object of the invention to provide a novel firearm in which 
the firing pin is urged by spring power to a firing position, and the 
firing pin is subjected to recoil action to unlock the bolt without 
imposing undue stress upon the spring. 
It is an additional object of the invention to provide novel means for 
obturating around a firing pin without requiring the placement of grooves 
in the firing pin. 
It is another object of the invention to provide an effective anti-recoil 
muzzle and means for resisting carbon build-ups on the reaction surface. 
It is still a further object of the invention to provide a novel propellant 
cartridge which is inexpensive to manufacture, leaves virtually no 
residue, and is easily handled within the firearm. 
BRIEF SUMMARY OF PREFERRED EMBODIMENTS 
These and other objects are achieved by the present invention in which a 
bolt is slidably mounted in a receiver and includes laterally open pockets 
which receive a projectile and a separate propellant cartridge from a 
magazine. An extractor is carried by the bolt to extract an unspent 
projectile. 
The extractor comprises a pin having a leg which contacts a wall of the 
receiver, and an integral extractor lip. When the bolt is retracted, 
contact between the leg and receiver wall causes the extractor lip to be 
rotated into engagement with a groove in the projectile. 
A bolt locking collar is provided which is mounted for rotatable, 
non-reciprocable movement. The bolt extends through the collar and is 
non-rotatable. Bolt locking lugs enter slots in the collar during 
advancement of the bolt and contact the collar in a manner rotating the 
collar to a position in which the locking lugs are retained within an 
offset locking portion of the slots. 
The collar is unlocked by the action of a firing pin which recoils in 
response to the firing of a shot. The firing pin engages a rotatable 
hammer which, in turn, contacts and rotates the collar. The collar is 
removable to facilitate servicing. 
The hammer is spring biased to a position in which it propels the firing 
pin in a firing direction. The relationship between the hammer and spring 
is such that the spring stores energy during only a portion of the rotary 
travel of the hammer. 
An obturation seal is mounted on the bolt in surrounding relation to the 
firing pin. The seal includes a deformable ring sandwiched between rigid 
rings. One of the rigid rings is exposed to ignition gas pressure to 
deform the deformable ring against the firing pin to effect a gas seal. 
The firearm includes a barrel which has an anti-recoil muzzle secured at a 
discharge end thereof. The barrel carries stiff bristles which scrub 
combustion deposits from a reaction surface of the muzzle. 
A propellant cartridge for use with a separate projectile includes a pair 
of open ended cylindrical jackets which are telescoped together to form a 
propellant-carrying chamber. An additional jacket is telescoped over the 
closed end of one of the other jackets to form a primer-carrying 
compartment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
One preferred form of firearm according to the present invention is 
illustrated in FIGS. 1-13. This firearm 10 is of the single shot repeater 
type and includes a receiver 12 and a barrel 14 attached to the forward 
end of the receiver. The receiver 12 includes a hand grip 16 and a trigger 
18. A stock 20 is detachably secured to the receiver by a bolt 22. The 
receiver contains a bore 24 which communicates with a bore 26 of the 
barrel. 
Firing Mechanism 
A bolt 28 is reciprocably mounted in the bore 24 of the receiver 12. The 
bolt 28 is urged to a forward, obturating position by means of a coil 
compression spring 30. 
Affixed rigidly to the bolt and extending radially therefrom in diagonally 
opposite directions are two locking lugs 32, 34, one 34 of which includes 
a cocking handle 36 (FIG. 7). The cocking handle 36 projects through a 
longitudinally extending slot (not shown) in the receiver and the outer 
end of the locking lug 32 rides in a receiver groove (not shown), to 
prevent rotation of the bolt 28 relative to the receiver, thereby 
restricting the bolt of longitudinal reciprocation. 
The bolt is encompassed at a rearward end thereof by a cylindrical locking 
collar 38. This locking collar 38 includes a central bore 40 through which 
the bolt extends for relative reciprocal movement. The locking collar 38 
is mounted for rotational movement within the receiver and relative to the 
bolt and is restrained against longitudinal movement by suitable means, 
such as by appropriately positioned shoulders 42, 43. 
The locking collar includes a pair of slots 44, 44'. Each slot comprises a 
rearwardly open, longitudinally extending portion 46 and a 
circumferentially extending portion 48 (FIG. 4), the latter being offset 
from the longitudinal portion and defining a locking recess. Each slot 
includes a wall 50 which, at its forward end, extends inwardly and 
helically. This wall 50 is oriented to be contacted by the associated 
locking lug 32 or 34, during forward travel of the latter within the slot 
44 o4 44', to produce rotation of the locking collar 38. That is, as the 
locking lug travels forwardly within the slot, under the urging of the 
bolt spring 30, and approaches the forward end thereof, it contacts the 
wall 50 and rotationally cams of the locking collar during the last stage 
of bolt forward travel. Accordingly, the locking recesses 48 are rotated 
into a position where stop surface 52 thereof become disposed across the 
rear end of each locking lug 32, 34. In this manner, rearward travel of 
the bolt 28 within the receiver is prevented. 
If, for reasons to be discussed, it is desired to retract the bolt in the 
absence of firing a shot, the locking collar can be manually rotated by 
means of an unlocking lug 54 (FIG. 7) which extends through a 
circumferential slot (not shown) in the receiver so as to be externally 
accessible. This allows the locking collar 38 to be suitably positioned 
for retraction of the bolt 28 by the cocking handle 36. 
A firing pin 56 is reciprocably mounted within a through-passage 157 (FIG. 
8) in the bolt 28 and has a forward end adapted to produce ignition of a 
propellant charge 58 during forward travel of the pin. Forward travel of 
the firing pin is produced by a hammer 60. The hammer 60 is rotatably 
mounted within the receiver and within a recess 61 in the bolt by a pivot 
pin 62. Acting against a rear edge of the hammer is a hammer spring 64. 
The hammer spring 64 comprises a coil compression spring which encompasses 
a slidable rod 66. The rod 66 is confined to reciprocable motion within a 
guide passage 68. At its upper end the rod carries a head comprising a 
U-shaped bracket 70 having a pin 72 extending between the legs of the 
U-bracket. A curved edge 74 of the hammer is received between the legs of 
the U-bracket and is engaged by the pin 72. In this fashion, the hammer is 
constantly biased toward a firing position (i.e., counterclockwise as 
viewed in FIG. 1) by the spring 64 which exerts its biasing force in a 
linear direction. 
The hammer 60 also includes a control extension 76 which overlies a sear 
portion 77 of the trigger 18 when the latter is in a rest or non-firing 
position (FIG. 1). A sear spring 78 biases the trigger to such rest 
position. When the hammer extension 76 overlies the sear, rotation of the 
hammer by the hammer spring is prevented. Upon actuation of the trigger to 
a firing position (FIG. 2), the sear is displaced from engagement with the 
hammer extension, allowing the hammer spring 64 to swing the hammer 60 to 
a firing position, whereupon an abutment face 80 of the hammer strikes the 
firing pin 56 and rams it forwardly to detonate a propellant charge, in a 
manner to be discussed. 
When detonation occurs, recoil of the bolt 28 by ignition gas pressure is 
prevented by the stop surface 52 of the locking collar. The firing pin, 
however, is responsive to such gas pressure and is rammed rearwardly into 
contact with the hammer and swings the hammer counter to the bias of the 
hammer spring 64 (i.e., the hammer is urged clockwise as viewed in FIG. 
3). The action of the firing pin against the hammer is sufficient to swing 
the hammer past its initial rest position (after camming the trigger aside 
if necessary) to an override position (FIG. 4), whereupon it acts upon the 
locking collar. 
In this connection, the locking collar 38 includes a downwardly projecting 
turn lug 82 which functions as a cam follower when the hammer is in its 
override position. That is, either the hammer or the turn lug, but 
preferably the hammer, includes a cam surface 84 which displaces the turn 
lug circumferentially as the hammer contacts the turn lug in approaching 
the end of its override position. This causes the slots 44, 44' of the 
locking collar to be rotated to positions wherein the locking lugs 32, 34 
of the bolt 28 become aligned with the longitudinal portions 46 of the 
slots. This enables the bolt 28 to be displaced rearwardly by residual 
ignition gas pressure. 
Due to the curved nature of the edge 74 of the hammer 60, the hammer spring 
64 is not compressed by an amount proportional to the entire rotational 
distance of travel of the hammer. That is, the hammer spring is compressed 
in response to an initial segment of travel of the hammer from the firing 
position, to about the position shown in FIG. 3. Thereafter, the pin 72 
contacts a generally circular segment 86 of the hammer 60, whose 
geometrical center is defined by the hammer pivot 62. Consequently, little 
additional compression of the spring 64 is produced. As a result, travel 
of the hammer 60 to its override position (FIG. 4) is facilitated, and the 
spring is not subjected to excessive stressing. 
It will be realized that upon reaching the end of its override position, 
the hammer 60 is returned by the hammer spring 64 to the rest position, 
whereupon it rests upon the sear 77 (assuming that the trigger has been 
released). 
The locking collar 38 is manually removable from the receiver 12. In this 
connection, an axially removable retainer sleeve 89, which defines the 
shoulder 43, can be disposed between the locking collar and the stock 20. 
By removing the stock, the retainer sleeve 89, and the bolt 28, the 
locking collar can be removed for servicing or replacement. 
Loading Mechanism 
The projectile-handling portion of the firearm will now be discussed with 
particular reference to FIGS. 1-4, 6, and 9-11. 
At its forward end the bolt 28 includes a pair of longitudinally spaced, 
laterally open pockets 90, 92 for the reception of a projectile 92 and the 
propellant cartridge 58, respectively. The projectile and cartridge are 
housed within a magazine 96 which is carried by the receiver 12 and which 
feeds laterally into the receiver bore 24. The magazine 96 includes dual 
compartments 98, 100 for storing projectiles and propellant cartridges, 
respectively. Both compartments include a feed spring 102, 104 which urges 
the projectiles 92 and cartridges 58 toward the receiver bore 24. 
A preferred form of propellant cartridge 58 will be discussed subsequently 
in detail. Suffice it to say, at this point however, that such a cartridge 
comprises an outer flexible cover which houses a propellant charge and a 
primer, the latter being ignitable in response to the compressive action 
of the firing pin 56. One acceptable form of cartridge answering this 
description is set forth in this inventor's U.S. Pat. No. 3,828,676 issued 
Aug. 13, 1974. 
The pockets 90, 92 are separated by a divider lip 106 which engages the 
rear of the projectile to advance the latter. This lip 106 extends only 
partially across the juncture of the pockets so that the pockets are in 
continuous communication with one another. 
Mounted on the magazine 96 in overlying relation to a feed opening 108 of 
the magazine is a trip plate 110. This plate 110 is pivotably mounted at 
one side (FIG. 6) and is rotatable between a closed position (solid line 
position of FIG. 6) in which the feed opening 108 is blocked, and an open 
position in which the feed opening is unblocked (broken line position of 
FIG. 6). When the bolt 28 is retracted, i.e., shifted rearwardly to a 
loading position (FIG. 1), the projectile and cartridge components force 
the trip plate 110 open under the urging of the magazine springs 102, 104 
and enter their respective pockets 90, 92. 
When the bolt 28 is advanced, a forwardly facing shoulder 112 of the 
cartridge pocket engages the back of the cartridge, and a forwardly facing 
wall of the divider lip 106 engages the back end of the projectile 92 to 
advance the projectile and cartridge. When the bolt 28 has been fully 
advanced so that the bolt locking lugs 32, 34 are received in the locking 
recesses 48 of the locking collar 38, the projectile will project slightly 
into the barrel bore 26 (FIG. 1). The barrel bore 26 and projectile 92 are 
dimensioned to provide a snug fit therebetween for effecting suitable 
obturation. 
The end 112 of the cartridge pocket includes, at one side, a projection 
(not shown) which engages an inclined face 113 of the trip plate to cam 
the trip plate downwardly as the bolt is advanced. 
It will be realized that when the projectile and cartridge are disposed in 
the firing or armed position (FIG. 1), detonation of the propellant charge 
by the firing pin produces high-pressure ignition gases which communicate 
with the rear of the projectile to expel the latter through the barrel. 
The cartridge materials are fully combustible so that the pockets are 
emptied, with no appreciable residue remaining. 
Projectile Extractor 
In the event that a misfire should occur, or it is desired for certain 
reasons to disarm the firearm subsequent to being placed in an armed 
condition, it is necessary that the projectile and cartridge be extracted. 
This is achieved by an extractor 120 depicted mainly in FIGS. 9-11. 
The extractor 120 comprises an inverted U-shaped pin which cooperates with 
an annular groove 122 in the projectile 92. This extractor pin 120 has a 
bight portion 124 which is received within a recess 126 adjacent the front 
end of the bolt 28. Legs 128 of the extractor pin extend downwardly from 
the bight portion in straddling relationship to the projectile 92. These 
legs 128 are arranged to contact and ride upon the bottom surface 130 of 
the receiver bore 24 and, in so doing, control the orientation of the 
bight portion. That is, the bight portion has an extractor lip 132 
extending across the underside thereof. When the bolt is displaced 
forwardly, the legs are disposed in a lightly rearwardly swept orientation 
(FIG. 1) and the extractor lip 132 is located above the projectile, i.e., 
the lip 132 is situated laterally of the projectile groove 132. When the 
bolt reaches the armed position, the bottom ends of the legs enter a notch 
134 within the receiver bore 24. In the event that a shot is not fired and 
extraction of the projectile 92 and/or cartridge 58 is required, the bolt 
28 is manually retracted by the cocking handle 36. In so doing, the bottom 
ends of the legs of the extractor pin contact the rear edges 136 of the 
notches, causing the extractor pin 120 to swivel about the bight portion. 
Consequently, the extractor lip 132 enters the annular groove 122 of the 
projectile and pushes the projectile rearwardly through the receiver bore 
as the bolt is retracted. During this travel, the legs of the extractor 
pin will be disposed in a slightly forward swept orientation relative to 
the bight portion (FIG. 11). 
To accommodate rejection of the projectile 92 and cartridge 58, the 
magazine 96 is removed from the receiver 12, thereby allowing the 
projectile and cartridge to fall through the opening previously occupied 
by the magazine. 
Firing Pin Retractor 
In the event that a misfire has occurred, it will also be necessary to 
retract the firing pin 56. This is accomplished by means of the hammer 60 
which carries a resiliently flexible hook 140. This hook engages a notch 
142 at the rear end of the firing pin as the hammer drives the firing pin 
forward (FIG. 8). 
Rotation of the hammer in the opposite direction retracts the firing pin. 
When the firing pin reaches a proper rearward position, the hook will be 
released from the firing pin due to the change in inclination of the hook 
caused by the curved path about the pivot axis 62 about which the hook 
travels. 
Obturation of Firing Pin 
A gas seal assembly 145 is provided to seal around the periphery of the 
firing pin 56 when a round has been fired (FIG. 8). This seal assembly 145 
comprises a plurality of individual rings 148, 150, 152 which are inserted 
into a forwardly open annular compartment 154 in the bolt 28. The 
compartment is concentric with the firing pin passage 57. The three rings 
148, 150, 152 include inner and outer rings 148, 152 formed of spring 
steel, and an intermediate ring 150 formed of a softer metal such as brass 
which can be compressed or deformed. The outer ring 148 is subjected to 
the pressure of ignition gases and functions to forcefully sandwich the 
intermediate ring 150 between itself and the inner ring 152 in a manner 
causing the intermediate ring to deform and tighten against the outer 
periphery of the firing pin 56. This action produces a sealing effect to 
resist rearward escape of gas and gas pressure through the firing pin 
passage 57. Contact of the intermediate ring 150 with the firing pin is 
not sufficient to unduly retard recoil of the firing pin by ignition gas 
pressure. 
Anti-Recoil Muzzle 
In order to counteract to some degree the recoil effects of detonation, a 
longitudinally displaceable muzzle 156 is mounted on the front end of the 
barrel. The muzzle includes a sleeve 158 which encompasses the front end 
of the barrel and is slidable longitudinally relative thereto. This sleeve 
158 includes an annular leg 160 which is slidable within a collar 162 that 
is fixed to the barrel. The collar has a radially inwardly extending 
shoulder 164 which retains the leg 160. A coil compression spring 166 is 
disposed within the collar 162 and acts between the shoulder 164 and the 
leg 160 to bias the sleeve rearwardly. The muzzle includes a reaction 
surface 168 which is spaced longitudinally from the end of the barrel and 
upon which the ignition gases act to urge the sleeve forwardly in response 
to firing a round. Resulting forward travel of the muzzle is transmitted 
to the barrel by the spring 166 and the collar 162 to aid somewhat in 
counteracting the recoil effects. 
Mounted on the front end of the barrel is a threaded barrel extension, or 
false muzzle 170, which carries an annular array of spring steel bristles 
172. These bristles, which can be on the order of 1 or 2 mm. in diameter, 
for example, project forwardly to form a steel brush which is engageable 
with the reaction surface 168. The reaction surface is preferably of a 
tapering nature, and the bristles become of progressively longer length in 
a radially inward direction. That is, the bristles nearer the axis of the 
barrel are longer than those further away from such axis. The bristles 172 
are of sufficient length to assure that as the sleeve is spring-urged 
rearwardly to a rest position, the tips of the bristles engage and scrape 
the reaction surface to resist the build-up of carbon or other deposits on 
the reaction surface. 
Significantly, the presence of the bristles reduces the effective area of 
the front surface 174 of the barrel extension. That is, there is less area 
of this surface against which ignition gases can act to counteract the 
anti-recoil action of the muzzle, since the area occupied by the bristles 
cannot be acted upon to produce recoil. Nor can the tips of the bristles 
be acted upon to produce recoil since the bristles are not sufficiently 
rigid to transmit axial forces to any appreciable degree. 
Modified Bolt 
A modified form of the bolt is depicted in FIGS. 14-17. In this embodiment, 
a cartridge pocket 176 is situated above the projectile pocket in 
piggy-back fashion. The cartridge pocket 176 is formed by front and rear 
ledges 178, 180 on the bolt so that the pockets are maintained in 
communication with one another via the space between the ledges. One 
effect of such a piggy-back or superimposed arrangement is a shortening of 
the effective stroke of the bolt, thereby shortening the overall cycle 
time. This is especially useful in machine guns since the rate of fire can 
be increased. 
A magazine 182 carries projectiles 92 which are fed into the projectile 
pocket as previously described. Feeding of the cartridge pocket takes 
place from above by means of a belt feed system 184. This belt feed system 
184 comprises a drum magazine (not shown) which houses a coiled belt 186 
formed of plastic. The belt 186 includes a plurality of resilient fingers 
188 forming recesses 190 that carry cylindrical propellant cartridges 58. 
In order to both feed the bolt and inject cartridges, a mechanism is 
provided which includes a rod 192 which is mounted to the receiver housing 
via a bearing block 194 for rotation about an axis A that is parallel to 
the barrel axis (FIG. 17). The rod carries a downwardly extending cam 
follower 196 which cooperates with the cocking handle 36 to produce 
rotation of the rod. Since the cocking handle is driven rearwardly with 
the bolt following the firing of a round, it will cam the cam follower and 
produce rotation of the rod. Mounted on the rod are a pair of drive cams 
198, 200. A first of the drive cams 198 is situated above the belt 186 and 
is capable of pushing a cartridge 58 from the belt into the cartridge 
pocket 176 when the rod 192 is rotated (FIG. 16). At the same time, the 
second control cam 200 actuates a belt feed pawl 202 to advance the belt 
186. The pawl is rotatably mounted at the end of an arm 204, the latter 
being pivotably mounted at 206 for rotation about an axis extending 
parallel to the axis of the barrel. The arm carries a finger 208 which 
extends toward the second control cam 200 so that when the second control 
cam rotates, it pivots the arm and pawl. The pawl is positionable within 
an emptied recess 190 and acts upon the wall thereof to advance the belt. 
A suitable spring 210 is provided to return the arm and cam 198 to their 
original position following a feeding step. The pawl is spring biased via 
a torsion spring (not shown) toward its position within a recess shown in 
FIG. 15 and is rotatable from that position, relative to the arm (i.e., 
rotatable counterclockwise as viewed in FIG. 15), so that the pawl can 
pass beneath a finger 188 and enter the next emptied recess 190 when the 
arm is returned to its FIG. 15 rest position. 
In this embodiment the firing pin is inclined upwardly from rear to front 
to contact the cartridge. 
Propellant Cartridge 
The preferred propellant cartridge 58 is generally cylindrical in 
configuration and carries a charge of propellant material and a primer 
compound (FIGS. 12-13). The cartridge includes first and second jackets 
220, 222 which are of cylindrical shape, each having open and closed ends. 
The first jacket 220 is smaller in diameter than the second jacket 222, 
enabling the open end of the first jacket 220 to be telescopingly received 
within the open end of the second jacket 222. This arrangement defines a 
chamber 224 which is occupied by the propellant charge, such as gunpowder. 
A third cylindrical jacket 226 is provided, having open and closed ends and 
being of substantially the same diameter as the second jacket 222. The 
closed end of the first jacket 220 is telescopingly received in the open 
end of the third jacket 226, with the open ends of the second and third 
jackets 222, 226 disposed in abutting relation. The third jacket 226 is of 
a length suitable for defining, together with the closed end of the first 
jacket 220, a compartment 228 which is occupied by a compression-ignitable 
priming compound. 
The cartridge 58 is inserted within the bolt 28 such that the 
primer-containing end thereof faces the firing pin 56. When the firing pin 
is actuated, it strikes the closed end of the third jacket 226 with great 
force, to compress the primer compound against the closed end of the first 
jacket 220, the latter functioning as an anvil. In response to this 
compression, the primer detonates and ignites the propellant charge. 
The jackets 220, 222, 226 are formed of a tough film of unpasticized high 
nitrogen nitrocellulose which exhibits a high tolerance to heat and low 
moisture permeability. This film burns at rates commensurate with 
conventional gunpowder without leaving an appreciable residue. The second 
and third jackets 222, 226 are suitably fused together or adhered by a 
nitrocellulose compound. Reference may be had to the inventor's U.S. Pat. 
No. 3,828,678 for further details concerning available residue-free 
materials for the cartridge. 
Barrel Mounting 
The barrel 14 is mounted by means of a quick release arrangement for 
exposing the interior of the firearm for cleaning and maintenance. The 
barrel includes a main part 230 and a screwed-on extension 232. The barrel 
extension 232 fits into recesses 234 in the receiver and is secured 
therein by a rotatable latch 236 (FIG. 18). The latch includes bearing 
portions 238 which are rotatably mounted in the receiver, and a bridge 
part 240 therebetween which, when the latch is rotated via a handle 242 to 
a locking position, blocks removal of the barrel. When the latch is 
rotated to an unlocking position, the bridge 240 is displaced so as to 
permit removal of the barrel. Accordingly, by retracting the bolt 28 clear 
of the barrel extension 232, and unlocking the latch 240, the barrel 14 
can be removed to permit servicing of the firearm parts of substitution of 
a cold barrel. 
OPERATION 
In operation of the embodiment disclosed in conjunction with FIGS. 1-13, 
the magazine 96 is loaded with projectiles 92 and cartridges 58 and is 
installed within the receiver 12. An initial charge is fed into the bolt 
by manually retracting the bolt 28 by the cocking handle 36. This done 
following manual rotation of the locking collar 38 by the manual lug 54 to 
align the locking lugs 32, 34 of the bolt with the longitudinal parts 46 
of the slots 44, 44'. 
When the pockets 90, 92 of the retracted bolt 28 arrive at a location above 
the magazine feed opening 108, the uppermost projectile 92 and cartridge 
58, under the urging of the magazine springs 102, 104 enter the respective 
pockets. Retraction of the bolt also causes the rear end of the bolt to 
engage the impact face 80 of the hammer 60 and rotate the hammer to a 
cocked posture against the bias of the hammer spring 64. Since the hammer 
60 is momentarily connected to the firing pin 56 by the retractor hook 
140, the firing pin is retracted to a ready or firing position. 
The bolt upon release is urged forwardly by the bolt spring 30 so that the 
locking lugs 32, 34 enter the slot of the locking collar. The locking lugs 
contact the cam follower surface 50 of each slot and rotates the collar 38 
to lock the bolt against retraction (FIG. 3). 
At the same time, the projectile 92 and cartridge 58 are advanced and the 
projectile enters the bore of the barrel extension 232. 
It will be realized that the projectile and cartridge are advanced by 
separate surfaces i.e., the front of the lip 106 and the surface 112 of 
the bolt, and, accordingly, the projectile enters the barrel without there 
occurring contact of the cartridge with the projectile or any other 
surface which could subject the cartridge to appreciable shock or 
compressive forces. Hence, there need be no requirement for the cartridge 
to be formed of highly rigid materials. 
With the firearm disposed in a ready condition, the trigger 18 can be 
depressed, enabling the hammer spring 64 to rotate the hammer 60 and ram 
the firing pin 56 against the cartridge 58. The cartridge as a whole is 
compressed between the lip 106 and the firing pin, and the primer compound 
is compressed between the firing pin and the closed end of the first 
cartridge jacket 220. Consequently, the primer detonates and ignites the 
charge. 
Ignition gas pressure communicates with the back end of the projectile to 
discharge the projectile through the barrel. Gas pressure also bears 
against the outer ring 148 of the seal assembly 145 of the bolt (FIG. 8) 
to deform the intermediate ring 150 against the outer periphery of the 
firing pin 56. Thus, a gas seal is created around the firing pin as the 
latter is displaced rearwardly by gas pressure. 
The rearwardly traveling firing pin 56 thrusts against the hammer 60 and 
imparts sufficient momentum to the hammer to carry it past the rest 
position and to the override position (FIG. 4) against the bias of the 
hammer spring 64. Thereupon, the hammer extension 76 engages the collar 
turn lug 82 and rotates the locking collar 38 to align the longitudinal 
parts 46 of the slots 44, 44' with the locking lugs 32, 34. This enables 
the bolt 28 to be retracted by residual chamber gas pressure so that a new 
projectile and cartridge can be inserted into the pockets from the 
magazine. 
Thereafter, the hammer is urged away from the turn lug 82 by the hammer 
spring 64 until stopped by the trigger (if the trigger has been released). 
If the trigger remains depressed, then the hammer continues rotating 
toward the firing pin and the firing sequence is repeated. 
When the projectile is discharged from the barrel, ignition gas pressure 
bears against the reaction surface 168 of the anti-recoil muzzle 158 (FIG. 
5) to advance the muzzle against the bias of the spring 166, to create 
anti-recoil forces. When the spring returns the muzzle, the reaction 
surface is scrubbed by the bristles 172 to remove carbon and other 
deposits. 
In the event that a misfire occurs, or it is decided not to fire a shot, 
the firearm can be disarmed or cleared by manually retracting the bolt 28 
via the bolt handle 36 (FIG. 7). In so doing, the extractor 120 (FIG. 9) 
swivels and the extractor lip 132 enters the groove 122 in the projectile 
92. The extractor thus pushes the projectile rearwardly. With the magazine 
removed, the projectile and cartridge will simply fall through the opening 
formerly occupied by the magazine. 
As this occurs, the bolt 28 engages and retracts the hammer 60. Since the 
latter is connected to the firing pin via engagement of the hook 140 
within the recess 142, the firing pin is retracted. This is necessary 
since no ignition gas pressure is available to retract the hammer or the 
firing pin. Eventually, the hook 140 releases the firing pin 56 in a 
firing position. 
SUMMARY OF MAJOR ADVANTAGES AND SCOPE OF THE INVENTION 
The present invention provides for the loading of separate projectile and 
cartridge elements without subjecting the cartridge to appreciable 
stresses, and provides for convenient extraction of an unspent round. It 
will be appreciated, that the bolt itself functions in the manner of a 
conventional metallic casing of cased ammunition in that it carries the 
projectile and propellant, isolates the propellant from excessive stresses 
and shocks and enables the round to be extracted if not fired. Thus, the 
present invention marries the advantageous features of caseless ammunition 
with the reliable operation of traditional cased ammunition. 
The present invention provides a simplified firing system in which a 
non-rotating bolt locks itself within a collar. This simplified locking 
arrangements greatly simplifies cleaning and servicing and also renders 
highly feasible the employment of replacement bolts. The practicality of 
having a substitute bolt depends to a large extent on the complexities of 
the locking system. That is, with a relatively simple locking system, it 
is much easier to fit locking lugs and locking recesses to acceptable 
tolerances in the manufacture of the gun than it is where multiple, 
relatively inaccessible surfaces must be machined to close tolerances. 
The conventional turning bolt, for instance, has buried locking recesses 
which complicate the coaptation fitting of locking lugs and locking 
recesses in the manufacture of the gun, and also complicate the cleaning 
of the gun. 
The proposed locking collar, which makes locking lugs and locking recesses 
visible, will facilitate the manufacture of an interchangeable bolt for 
that firearm. Moreover, since the locking collar is removable once the 
bolt is withdrawn, the locking collar and all bearing surfaces in the 
collar and fixed receiver will be readily available for field servicing 
and cleaning. 
In the proposed firearm, then, a clean cool bolt, in effect a fresh 
chamber, can rapidly be substituted for the original bolt after a 
sustained period of firing without more than momentary interruption of 
firing. 
In addition, after bolt withdrawal, a fresh cool barrel with its barrel 
extension which functions as the outer chamber walls can be installed 
without undue interruption of fire in the machine gun. 
This will mean that all heated components of the gun are quick replaceable 
with fresh elements -- an important objective particularly in the infantry 
machine gun where periods of firing may be indeterminate, and overheating 
might otherwise render the gun inoperable. 
Moreover, the firing pin performs a dual function in that it detonates a 
propellant cartridge and unlocks the bolt subsequent to firing a shot. 
Advantageously, such dual function of the firing pin is accomplished in a 
firearm wherein the firing sequence is initiated with the bolt situated in 
a forward, closed position. In addition, there are no springs acting 
directly against the firing pin and which are energized proportionally to 
firing pin displacement for the entire stroke of firing pin retraction. 
Rather, the hammer spring acts upon the hammer and is energized in 
proportion to clocking movement of the hammer for only a portion of the 
hammer stroke. The hammer spring is maintained at a substantially constant 
compression during the remainder of the stroke. As a result, the velocity 
and stresses to which the spring will be subjected will be minimized. 
The anti-recoil muzzle incorporates an effective carbon cleaner and 
minimizes recoil action. 
A new cartridge is provided which is of a shape that facilitates feeding, 
is inexpensive to manufacture, and leaves minimal residue. 
An effective seal assembly for obturating around the firing pin is provided 
which eliminates the need for forming grooves in the firing pin to receive 
sealing rings and the accompanying weakening of the pin. 
Although the invention has been described in connection with a preferred 
embodiment thereof, it will be appreciated by those skilled in the art 
that additions, modifications, substitutions and deletions not 
specifically described may be made without departing from the spirit and 
scope of the invention as defined in the appended claims.