U.S. patent number 3,592,101 [Application Number 04/817,770] was granted by the patent office on 1971-07-13 for gas system for autoloading firearm.
This patent grant is currently assigned to Olin Corporation. Invention is credited to Jay P. Jarvis, Edwin S. Vartanian.
United States Patent |
3,592,101 |
Vartanian , et al. |
July 13, 1971 |
GAS SYSTEM FOR AUTOLOADING FIREARM
Abstract
A gas system for an autoloading firearm wherein the gas piston
is operative to seal the gas cylinder against high-pressure
combustion gases during early stages of recoil of the firearm after
firing thereof. As the force of recoil decreases, the seal is
broken and lower pressure gases are bled into the gas cylinder to
actuate the gas system.
Inventors: |
Vartanian; Edwin S. (North
Haven, CT), Jarvis; Jay P. (Madison, CT) |
Assignee: |
Olin Corporation (N/A)
|
Family
ID: |
25223846 |
Appl.
No.: |
04/817,770 |
Filed: |
April 21, 1969 |
Current U.S.
Class: |
89/193 |
Current CPC
Class: |
F41A
5/26 (20130101) |
Current International
Class: |
F41A
5/00 (20060101); F41A 5/26 (20060101); F41d
005/08 (); F41d 005/10 () |
Field of
Search: |
;89/191,192,193 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Bentley; Stephen C.
Claims
What I claim is:
1. In an autoloading firearm having a receiver and a barrel with a
bore rigidly connected to the receiver, a gas system for operating
the action of the firearm, said gas system comprising:
a. a gas cylinder rigidly secured to the barrel, said gas cylinder
including a gas chamber having a cylindrical sidewall;
b. port means interconnecting said gas chamber and the barrel bore,
said port means opening into said gas chamber in an area completely
contained within said gas chamber sidewall, said port means being
operative to bleed pressurized combustion gases from the barrel
bore to said gas chamber;
c. shoulder means in said gas chamber and overlying a portion of
said port means opening;
d. piston means having a working face and slidably mounted in said
gas chamber, said piston means being movable into abutting contact
with said shoulder means; and
e. inertia body means operative to force said piston means against
said shoulder means during recoil to substantially seal said port
means from said gas chamber.
2. The gas system of claim 2, further comprising passage means
operative to continuously provide venting of said gas chamber to
control energy input in said gas chamber.
3. The gas system of claim 1, wherein said gas cylinder further
includes a void adjacent said port means opening, and bounded on
one end by a transverse end wall of said gas chamber, and bounded
on the other end by said working face of said piston.
4. In an autoloading firearm having a receiver and a barrel with a
bore rigidly connected to the receiver, a gas system for operating
the action of the firearm, said gas system comprising:
a. a gas cylinder rigidly secured to the barrel, said gas cylinder
having a gas chamber with a cylindrical sidewall;
b. port means opening into said cylindrical sidewall and
interconnecting said gas chamber with the barrel bore;
c. plug means rigidly secured to one end of said gas cylinder and
extending into said gas chamber, said plug means including an inner
portion overlying a part of said port means opening and defining a
shoulder;
d. piston means slidably mounted in said gas chamber in sealing
engagement with said cylindrical sidewall, said piston means being
movable into abutting contact with said shoulder; and
e. inertia body means movably mounted on said firearm and operative
to force said piston means against said shoulder during recoil to
substantially seal said port means from said gas chamber.
5. The gas system of claim 4, wherein said plug means is hollowed
out to form a void adjacent said port means opening and bounded on
one end by said piston means.
6. The gas system of claim 4, further comprising passage means
through said plug means operative to continuously vent said gas
chamber to control energy input in said gas chamber.
7. In a system for operating the action of an autoloading firearm
having a receiver, said system comprising:
a. a barrel having a bore rigidly secured to said receiver;
b. bolt means slidably mounted in said receiver for movement
between a battery position and a retired position;
c. means operative to lock said bolt means to the receiver when
said bolt means is in its battery position;
d. slide arm means connected to said bolt means;
e. gas cylinder means rigidly connected to said barrel, said gas
cylinder means having a gas chamber with a cylindrical
sidewall;
f. port means opening into said cylindrical sidewall and
interconnecting said barrel bore with said gas chamber;
g. shoulder means in said gas chamber and overlying a portion of
said port means opening;
h. piston means slidably mounted in said gas chamber, said piston
means being movable into abutting contact with said shoulder means;
and
i. inertia block means slidably connected to said slide arm means,
said inertia block means being operative to force said piston means
against said shoulder means during recoil to substantially seal
said port means from said gas chamber.
Description
This invention relates to a gas system for an autoloading firearm
which utilizes relatively lower gas pressures to operate. The
system of this invention may also provide a time lag between the
time that pressurized gas is first bled into the gas cylinder and
the time at which the gas is able to actuate the system.
In general, gas systems for operating the action of an automatic or
semiautomatic, autoloading firearm are old in the art. The
combustion gases resulting from firing the cartridge are bled from
the gun barrel through a port and into a gas cylinder mounted on
the barrel. The pressurized combustion gases are then operative to
move a piston through the gas cylinder to thereby cause the action
of the gun to move through the rearward portion of its
reciprocation cycle. The action is then moved through the forward
or return portion of its operating cycle by a spring. When the
action reaches the rearwardmost point of its reciprocation cycle,
it strikes a recoil block on the receiver of the firearm and begins
moving forward under the influence of the spring. The action of the
firearm and the recoil block are thus subjected to substantial
impact forces during reciprocation, which forces, if not kept at a
minimum, can greatly shorten the life of the firearm.
The magnitude of the impact forces to which the action and the
receiver are subjected is directly proportional to the pressure of
the combustion gases which operate the gas system. When the
cartridge is fired, the pressure of the combustion gases reaches a
peak value when the bullet is approximately an inch from the
cartridge casing, and then the pressure begins to drop off as the
bullet moves forward through, and exits from the barrel bore. A
bullet of any given caliber may be fired with a variety of powder
charges, depending on the bullet weight and the desired muzzle
velocity to be attained. The type and amount of powder in a given
shell influences the magnitude and duration of the pressure.
One of the prime factors controlling the rate at which gas pressure
decreases after the cartridge is fired is the relative diameter of
the barrel bore when compared to the chamber diameter. A barrel
bore having a given diameter will exhaust a comparatively smaller
diameter chamber more quickly than a comparatively larger chamber.
It is thus readily apparent that the gas pressure as measured at
any given point along the barrel bore at any given time after the
cartridge is fired will be higher for a cartridge having a larger
powder charge than for a cartridge having a smaller powder charge,
due to the fact that the large cartridge generates a higher peak
pressure and/or a larger volume of gas which is exhausted at a
slower rate.
As previously noted, it is desirable to operate the action of the
firearm with a minimum gas pressure in order that the action and
receiver not be subjected to violent shocks during reciprocation.
The gas pressure as measured along the barrel bore at any given
time after the cartridge is fired, lessens as the distance between
the point of measurement and the chamber increases. Furthermore the
gas pressure at any given point in the barrel bore decreases with
increase of the time interval between measurement and firing of the
cartridge. Thus one can decrease the gas-operating pressure for a
given cartridge by moving the gas bleed port further away from the
chamber, or by delaying the entry of combustion gases into the gas
chamber. The former solution does not accommodate itself to the
mass production of firearms, since the bleed port location, slide
arms, forearm, and other components of the gas system would
necessarily be customized for the same caliber gun chambered to
fire different powder charges. Accomplishment of the latter
solution is a primary object of this invention.
Another problem which is found to occur with different cartridges
having the same caliber bullet relates to extraction of the
cartridge casing from the chamber. When the cartridge is fired, the
gas pressure generated causes the casing to expand against the
chamber wall to seal the chamber from the bolt face. When the gas
pressure decreases the casing contracts so that it is extractable
from the chamber. The lower the chamber pressure, the easier the
extraction, thus it is desirable that the cartridge be extracted
after a time delay which is sufficient to permit the chamber
pressure to drop to a reasonably low level.
The gas system of this invention operates to seal the gas cylinder
against admittance of combustion gases during the period in which
gas pressure within the chamber and bore is above a predetermined
level. The system provides that the gas cylinder remain sealed even
after the bullet has passed the gas port and exited through the
muzzle. The gas system of this invention may also provide for a
time lag between the time that combustion gases first enter the gas
cylinder and the time that the gases can force the gas piston to
move rearwardly in the cylinder, thereby further delaying
reciprocation of the action to permit further dropping of the
chamber pressure. The system includes a gas cylinder which is
mounted on the firearm barrel at a predetermined distance forward
of the chamber. The cylinder houses a gas piston which reciprocates
therein and which includes a stem portion projecting from one end
of the cylinder and toward the receiver. The other end of the
cylinder is sealed with a plug. The piston is movable from one
extreme position where its working face seats against an inner
shoulder on the plug, to another extreme position wherein its stem
projects to its fullest extent toward the receiver. For purposes of
this disclosure, the face of the piston against which pressurized
gas acts to drive the piston is termed the "working face" of the
piston. A gas bleed port interconnects the barrel bore and the
interior of the gas cylinder, the port opening into the cylinder
interior in the area of the inner shoulder of the plug, preferably
with the inner portion of the plug partially covering the port. The
opening defined by the intersection of the port with the cylinder
interior is completely contained within the sidewall of the
cylinder interior so that gases within the port cannot act directly
upon the piston work face. In order to act upon the work face, the
gases must first enter the cylinder interior. An inertia body is
movably mounted on a rod below the barrel and between the gas
cylinder and the receiver, and a spring engages the inertia body to
bias the latter against the protruding stem of the piston. Thus the
spring and inertia body serve to bias the piston against the inner
shoulder of the plug to close off the port. The inertia body is
loosely connected to the bolt in such a way so as to permit the
inertia body a limited extent of forward longitudinal movement with
respect to the bolt. The connection also serves to transmit
extensive rearward and forward longitudinal movement of the inertia
body to the bolt so that the latter is reciprocated when the
inertia body is driven rearwardly and forwardly over its rod by the
piston and spring respectively.
When the gun is fired, the receiver, barrel and stock recoil
rearwardly. Since the bolt is locked to the receiver, and since the
gas cylinder and plug are rigidly secured to the barrel, the bolt
and the gas cylinder and plug also recoil to the rear. The piston,
however, is movably mounted in the cylinder, and the inertia body
is mounted on its rod for limited forward movement with respect to
the bolt, therefore the inertia body and piston "move" forward
relative to the rest of the gun during recoil. The inertia body
thus forces the piston against the inner shoulder of the plug to
substantially seal the port against entry of combustion gas. Of
course, the total sealing force exerted on the piston can be varied
by varying the mass of the inertia body. As the recoil decelerates,
the opposite sealing force of the inertia body and piston also
decreases, until a point is reached where the seal is ineffective
to keep combustion gases from entering the cylinder interior. When
this point is reached, the pressure of the gases in the barrel bore
and port has declined to a comparatively low value. When the
comparatively low pressure gases enter the cylinder interior, they
are free to act upon the work face of the piston to drive the
latter rearwardly through the cylinder, and the piston in turn
drives the inertia body rearwardly over its rod. This rearward
movement of the inertia body is operative, through the connection,
to drive the bolt through the rearward portion of its reciprocation
cycle. The bolt then impacts the recoil block on the receiver to
terminate rearward movement and permit the spring to move the
inertia body and bolt forward to their respective initial
positions. In order to further delay reciprocation of the action,
the plug or piston, or both, can be hollowed out to form a void in
the interior of the cylinder, which void must be filled before the
piston will be driven by the combustion gas. The size of the void
can be varied to alter the duration of the delay in initiation of
reciprocation.
The time period during which the gas cylinder is sealed after
firing the gun will increase as the size of the charge in the
cartridge increases for the reason that, other things being equal,
the larger the powder charge, the greater the recoil force; and the
greater the recoil force, the greater the sealing force exerted by
the piston and inertia body. Of course, the converse of the above
is also true, so that a small powder charge will cause a lesser
recoil, a lesser sealing force, and the seal will break sooner so
as to ensure that sufficient gas pressure is available to operate
the action.
It is, therefore, an object of this invention to provide a gas
system for autoloading firearms which operates at a lower gas
pressure despite variations in the size of the powder charge
utilized by cartridges in the firearms.
It is a further object of this invention to provide a gas system of
the character described which seals the gas cylinder against entry
of combustion gases until after the bullet has exited through the
muzzle and combustion gas pressure has dropped.
It is yet another object of this invention to provide a gas system
of the character described wherein the duration during which the
gas cylinder is sealed is proportional to the gas pressure
developed by firing the cartridge.
It is still another object of this invention to provide a gas
system of the character described wherein a time lapse may be
provided between the time combustion gases first enter the cylinder
and the time the combustion gases are able to act upon the piston
to drive the latter.
These and other objects and advantages of this invention will
become more readily apparent from the following detailed
description and accompanying drawings, in which:
FIG. 1 is a vertical sectional view of a portion of a firearm
utilizing the gas system of this invention and showing the firearm
after a cartridge has been fired and the bullet has passed the gas
port;
FIG. 2 is an enlarged vertical sectional view of the gas cylinder
area of the firearm of FIG. 1 showing the manner in which the gas
port is sealed from the interior of the gas cylinder during a
portion of recoil of the firearm; and
FIG. 3 is a vertical sectional view similar to FIG. 2 but showing
the seal being broken as the force of recoil declines after the
bullet has passed from the muzzle of the firearm.
Referring now to FIG. 1, a semiautomatic firearm is shown having a
barrel 2 with a bore 4, a receiver 6 connected to the barrel 2, and
a bolt assembly 8 reciprocally mounted in the receiver 6. The rear
portion of the receiver forms a recoil block 10 which the bolt 8
impacts at the rearward end of its reciprocation cycle. The bolt 8
is shown locked by conventional lugs 12 in its battery position,
and a cartridge casing 14 is seated in the chamber 16. The
cartridge has just been fired as shown in FIG. 1, and the bullet 18
has traveled down the barrel bore 4 to point beyond a gas bleed
port 20 opening into the barrel bore 4. Thus, as shown in FIG. 1,
the gas port 20 is exposed to high-pressure combustion gases
trapped between the cartridge casing 14 and the bullet 18. A gas
cylinder 22 is rigidly mounted on the barrel 2. An inertia body 24
of predetermined mass is slidably mounted on a rod 26 extending
between the receiver 6 and the gas cylinder 22, and a spring member
28 is sandwiched between the receiver 6 and the inertia body 24 to
bias the latter toward the gas cylinder 22. The inertia body 24
includes a pin 30 which extends into an elongated slot 32 in a
slide arm 34, the latter of which is connected to the bolt assembly
8. Thus the inertia body 24 is free to move longitudinally forward
over a limited distance even though the bolt 8 is locked to the
receiver b. The forward movement of the inertia body 24 is
accomplished by means of the pin 30 and slot 32; however, this
movement may be provided by any of a number of ways without
departing from the spirit of this invention. For example, the
inertia body could be rigidly secured to the slide arm which in
turn could be slidably secured to the bolt, as, for example, by
means of a sliding bolt carriage.
Referring now to FIG. 2, the gas cylinder 22 is hollowed out to
form a chamber 35 having a cylindrical sidewall 36. The gas bleed
port 20 is extended at 20' through the cylinder 22 to open into the
chamber 35 through the sidewall 36. It is noted that the gas port
20, 20' opening is completely contained in the sidewall 36. A plug
38 is threaded into the forward end of the cylinder 22 with the
inner face of the plug 38 terminating in the area of the gas port
20, 20' to define a shoulder 40. As shown in FIG. 2, a portion of
the plug 38 preferably overlies a portion of the gas port 20, 20',
however, the inner plug face shoulder 40 can be disposed closely
adjacent to the gas port 20, 20' without departing from the spirit
of the invention. A sealing ring 42 is preferably sandwiched
between the gas cylinder 22 and the plug 38 to seal the forward end
of the cylinder chamber 36. The plug 38 is hollowed out to form a
void 44 which provides a delay in reciprocation of the action, as
will be more clearly pointed out hereinafter. A pressure reduction
passage 45 is drilled through the forward end wall of the plug 38
so that the void 44 is vented to the exterior. The passage 45
provides for controlled reduction of gas pressure and resultant
energy input in the void 44 and gas chamber 35, and permits the gas
bleed port 20 and 20' to be greater in diameter than would
otherwise be possible with high-pressure cartridges. Thus the
diameter of the gas bleed port 20, 20' is rendered substantially
noncritical and the bleed port 20, 20' can be of a standard
diameter. It is noted that, while the plug 38 is hollowed out in
the preferred embodiment of the gas system, the void 44 may be
omitted from the plug 38 without departing from the spirit of the
invention. A piston 46 is slidably mounted in the gas chamber 35,
the piston having a groove 48 in which is seated a gas-sealing ring
50 operative to form a gastight seal with the chamber wall 35. The
piston 46 also includes a stem portion 52 which protrudes
rearwardly from the cylinder 22 through an opening 54. The rear
face 56 of the piston stem 52 is thus disposed for contact with the
inertia body 24.
As shown in FIG. 2, when the firearm is fired, the receiver, the
barrel, the gas cylinder 22, and all parts of the firearm rigidly
connected to the receiver, accelerate in the direction of the arrow
58 during recoil caused by the pressurized combustion gases. Since
the inertia body 24 and piston 46 are not rigidly connected to the
receiver, the inertia body 24 and piston 46 move (relative to the
rest of the firearm) in the direction of the arrow 60. The working
face 47 of the piston 46 is thus forced against the plug shoulder
40 so that the piston face 47 and plug shoulder 40 combine to seal
off the gas port 20, 20' from the cylinder chamber 35. In order to
be effective, the seal thus formed need not be perfect, rather it
must merely prevent more than just a trickle of pressurized gas
from entering the cylinder chamber 35. It is noted that the
pressurized gas in the gas port 20, 20' can only exert a force upon
the piston 46 which is normal to the axis of the piston, thus the
pressurized gas, while confined to the gas port, cannot force the
piston 46 to move rearwardly through the chamber 35.
As the recoil force declines, the seal between the piston face 47
and the plug shoulder 40 becomes less effective to exclude the
pressurized gas from the chamber 35, but at the same time the
pressure of the combustion gas is lowering. Finally a condition
shown in FIG. 3 is reached where the seal is broken and the
combustion gas is free to pass between the piston working face 47
and the plug shoulder 40 and into the cylinder chamber 35, the gap
between the face 47 and shoulder 40 being greatly exaggerated in
FIG. 3. After the gas passes the shoulder 40, the void 44 must fill
up before the gas will be able to drive the piston 46 rearwardly
through the chamber 35. Thus the presence of the void 44 provides a
delay in reciprocation of the action. When the void 44 is filled
with combustion gas, the latter will drive the piston 46 rearwardly
through the chamber 35 and the piston stem 52 will in turn drive
the inertia body 24 rearwardly over the rod 26. The momentum
imparted to the inertia body 24 by the piston 46 will carry the
inertia body 24 and the bolt 8 through the entire rearward portion
of their reciprocation cycle.
It is thus readily apparent that the gas system of this invention
permits lower pressure gases to operate the piston by sealing the
bleed port during a portion of the recoil movement after the weapon
is fired. Since the force of recoil is the same force that
initiates and maintains the seal, the seal will be greater for a
higher pressure cartridge and will block combustion gases from
entering the gas chamber for a longer period of time when a higher
pressure cartridge is fired. Still further, the provision of a void
in the system adjacent the working face of the piston causes a
further delay in actuation to occur after the gas first enters the
gas chamber. Inclusion of a pressure reduction passage to vent the
gas chamber permits control of the energy input in the gas chamber
without unduly restricting the size of the gas bleed port.
* * * * *