U.S. patent application number 13/431845 was filed with the patent office on 2012-07-19 for charging mechanism for gas powered firearms.
Invention is credited to Ethan A. Dublin.
Application Number | 20120180647 13/431845 |
Document ID | / |
Family ID | 46489754 |
Filed Date | 2012-07-19 |
United States Patent
Application |
20120180647 |
Kind Code |
A1 |
Dublin; Ethan A. |
July 19, 2012 |
CHARGING MECHANISM FOR GAS POWERED FIREARMS
Abstract
An improved mechanism for charging a gas powered firearm,
especially with regard to the Kalashnikov variants of rifles known
as AK-47s, comprising a modified gas tube having a lateral aperture
formed into its left side, a sleeve suitably adapted to fit within
the modified gas tube over the shaft of the operating rod, and a
modified charging handle suitably adapted to connect to the sleeve
and to extend from the firearm through the lateral aperture, such
that the firearm may be manually charged from the left side by
drawing the charging handle rearward; and providing safety
improvements and a method of retrofitting firearms.
Inventors: |
Dublin; Ethan A.;
(Cherryfield, ME) |
Family ID: |
46489754 |
Appl. No.: |
13/431845 |
Filed: |
March 27, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12540443 |
Aug 13, 2009 |
8141474 |
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13431845 |
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Current U.S.
Class: |
89/191.01 |
Current CPC
Class: |
F41A 3/72 20130101; F41A
5/18 20130101 |
Class at
Publication: |
89/191.01 |
International
Class: |
F41A 5/18 20060101
F41A005/18 |
Claims
1. A charging mechanism for a firearm, comprising: a generally
hollow gas tube including: a sidewall having a first and a second,
opposing distal end, and an elongate lateral aperture extending
through the sidewall, into the hollow portion of the gas tube; a
generally hollow charging tube having a charging handle extending
generally laterally therefrom, the charging tube being slidably
disposed within the hollow portion of the gas tube, the charging
handle extending through the lateral aperture of the gas tube; an
elongate, slidable gas piston assembly slidably disposed within the
hollow portion of the charging tube; a bifurcated sleeve having a
first portion and a second portion, the first and second portions
being attached to the gas piston assembly in opposition to one
another; and a locking bushing slidably engaging the first and
second portions of the bifurcated sleeve, the locking bushing
securing the first and second portions to the gas piston assembly,
the charging tube being slidable along the hollow portion of the
gas tube to selectably engage the locking bushing, thereby urging
the gas piston assembly away from the first distal end of the gas
tube, the charging tube being reciprocably slidable within the gas
tube.
2. The charging mechanism of claim 1 wherein the gas tube further
includes: a cocking notch extending through the sidewall and into
the hollow portion of the gas tube, the cocking notch being in
communication with the lateral aperture, and the charging handle
being selectably retained by the cocking notch.
3. The charging mechanism of claim 1, further comprising a sight
rail section coupled to the gas tube.
4. The charging mechanism of claim 1 wherein the gas tube further
includes a rear collar, the lateral aperture further extending
through the collar, into the hollow portion of the gas tube.
5. A charging mechanism for a firearm, comprising: a generally
hollow gas tube including: a sidewall having a first and a second,
opposing distal end, and an elongate lateral aperture extending
through the sidewall, into the hollow portion of the gas tube; a
generally hollow charging tube having a charging handle extending
generally laterally therefrom, the charging tube being slidably
disposed within the hollow portion of the gas tube, the charging
handle extending through the lateral aperture of the gas tube; and
an elongate, slidable gas piston assembly slidably disposed within
the hollow portion of the charging tube, the gas piston assembly
including an integral cylinder block, the charging tube being
slidable along the hollow portion of the gas tube to selectably
engage the cylinder block, thereby urging the gas piston assembly
away from the first distal end of the gas tube, the charging tube
being reciprocably slidable within the gas tube.
6. The charging mechanism of claim 1 wherein the gas tube further
includes: a cocking notch extending through the sidewall and into
the hollow portion of the gas tube, the cocking notch being in
communication with the lateral aperture, and the charging handle
being selectably retained by the cocking notch.
7. The charging mechanism of claim 5, further comprising a sight
rail section coupled to the gas tube.
8. The charging mechanism of claim 5 wherein the gas tube further
includes a rear collar, the lateral aperture further extending
through the collar, into the hollow portion of the gas tube.
Description
[0001] This application is a Continuation in Part of U.S. patent
application Ser. No. 12/540,443, filed Aug. 13, 1999, the entire
contents of which are incorporated herein by reference.
FIELD
[0002] The present invention relates generally to firearms, and
specifically to an improved mechanism for charging a firearm,
especially with regard to the variants of Kalashnikov rifles
generally referred to as AK-47 models.
BACKGROUND
[0003] AK-47 rifles are gas operated firearms in which the
discharge gases from a fired round of ammunition serve to cycle the
firearm's bolt and automatically eject the spent cartridge casing
from the just fired round and to chamber the next round from a
magazine. The standard charging mechanism of an AK-47 is fairly
straightforward. These firearms comprise a barrel in communication
with a firing chamber, or breach, and a bolt used to provide access
to the breach. The barrel is fitted with a port or similar aperture
which permits a portion of the discharge gases created from the
firing of a round of ammunition to escape the barrel through the
port. The port is in communication with an adjacent gas block,
which in turn is in communication with an adjacent, substantially
cylindrical gas tube. Contained within the gas tube is an gas
piston. The gas piston has a forward piston portion having an
outside diameter substantially the same, but slightly smaller, as
the inside diameter of the gas tube. The rearward end of the gas
piston is in sliding connection with the bolt assembly. The gas
piston is designed to reciprocate between a forward and rearward
position within the gas tube, with its rearward movement designed
to simultaneously force the bolt assembly rearward, which in turn
compresses a recoil spring mechanism. The recoil spring mechanism,
in turn, forces the bolt assembly to return forward to its firing
position which, in turn, moves the gas piston forward within the
gas tube.
[0004] A standard AK-47 must be charged in order to operate.
Charging of the firearm comprises the loading and reloading of
ammunition into the firing chamber and occurs as a result of a
cycling of the bolt assembly described above. During operation,
charging is occurs automatically utilizing the discharge gases of a
fired round of ammunition. When a round is fired, the cartridge
casing remains in the chamber of the barrel as the gases formed by
the explosion force the bullet to travel down the length of the
barrel. As the bullet passes the barrel port, a predetermined
portion of the discharge gases escape through the port and pass
through the gas block into the gas tube, where they then impinge
upon the piston portion of the gas piston, driving it rearward.
This rearward travel of the gas piston moves the bolt rearward,
opening the breach, extracting the spent cartridge casing from the
breach, ejecting the spent cartridge from the ejection port of the
weapon and compressing the recoil spring mechanism in connection
with the rear portion of the bolt. While the bolt is thus in its
rearward position and the breach is opened, a new round may be
readied into the breach by action of a spring mechanism in an
ammunition magazine. As the bolt returns forward the uppermost
round from the ammunition magazine is stripped therefrom and fed
into the chamber of the barrel. This cycling process typically
continues until all of the ammunition is expended and both the
ammunition magazine and the firing chamber are emptied.
[0005] The automatic loading cycle of each round of ammunition
described above takes place upon the firing of the previous round.
However, since the normal position of the firearm at rest is with
the bolt in a closed position, urged forward by the recoil spring
mechanism, the initial charging of the firearm must be accomplished
manually. Initial charging of a standard AK-47 is accomplished by
manually drawing the bolt assembly rearward. This is done by
manually grasping and drawing back a charging handle located on the
right rear side of the AK-47, which is directly linked to the bolt
assembly. Manually cycling the charging handle rearwardly first
"cocks" the firing mechanism and then releasing it results in the
loading of a round from the magazine into the breach as described
above. Once the bolt returns forward to its completely closed
position, the firearm is loaded and ready for firing. In addition
to manually charging an AK-47 for an initial round, it may also be
necessary to manually charge the weapon due to a misfire or misfeed
of a round from the magazine to clear a defective round from the
breach.
[0006] The current state of the art for manually charging an AK-47
is less than ideal. One significant issue is due to the charging
handle being located on the right side of the firearm. A
right-handed operator typically holds the pistol grip of the
firearm with their right hand and supports the front stock portion
of the firearm with their left. Under operational conditions, such
as during combat or during sporting events where time is of the
essence, the butt of the rifle preferably remains in firing
position against operator's right shoulder with the right hand
remaining on the pistol grip at all times. In this operational
condition, the left hand is used to reload the weapon with a fresh
magazine and then manually charge the firearm. In order to manually
charge the firearm in this manner, the operator's left hand must
move from the barrel supporting position, over or under the firearm
receiver to grasp the charging handle. The use of the left hand in
the described manner enables the operator to keep their right hand
on the pistol grip in a ready to fire position, but usually results
in the loss of sight picture and an unbalanced firearm because of
the awkward movement of the operator's left hand over or under the
receiver to the right side to engage the charging handle. This
method of charging the AK-47 not only runs the risk of losing the
site picture but also results in slower charging due to the amount
of distance the left hand must travel.
[0007] Another deficiency of the charging mechanism of the standard
AK-47 rifle is that the gas tube of the standard AK-47 rifle has a
closed cylindrical configuration. It has no opening to allow for
easy access to its interior for purposes of cleaning or allowing
air flow to cool the firearm. Since the discharge gases contain
spent powder residue, the greatest amount of debris and fouling
occurs within the gas block and the interior of the gas tube. This
residue stays in the gas tube and tends to accumulate after each
round is fired. If the gas tube and gas block are not periodically
cleaned, the charging mechanism of the firearm will fail to operate
properly, resulting in improper or even unsafe operation of the
weapon. In order to clean this residue the firearm must be
disassembled so that a cleaning cloth can be inserted into the gas
tube. This is a time consuming operation and requires frequent
periods of inactivity of use of the firearm. Moreover, the closed
configuration of the gas tube prevents ready visual inspection of
the firing chamber, that is, one cannot visually inspect the
chamber to determine whether cleaning is needed or even if a round
is loaded therein without some degree of disassembly of the
firearm. This presents a potential safety issue.
[0008] Another deficiency of the charging mechanism of the standard
AK-47 rifle is that the receiver is not provided with a bolt
locking mechanism, that is, at rest the bolt is always positioned
forward in its closed position, pressing against the chamber as a
result of the urging by the recoil spring mechanism. On the
standard AK-47 there is no way to keep the bolt open unless the
operator manually applies a constant rearward force on the charging
handle. Upon the operator releasing the charging handle
(intentional or not) the bolt assembly, under pressure from the
recoil spring mechanism, rapidly returns to its forward, closed,
position.
[0009] The standard AK-47 rifle is provided with a safety lever
located on the right side of the receiver of the firearm proximate
the charging handle. When the safety lever is engaged in its "safe"
position, the trigger and associated firing mechanism are locked
and cannot be actuated. So positioned the safety lever also serves
to block the rearward travel of the charging handle. This prevents
the charging handle from being fully drawn rearwardly to chamber a
round when the safety lever is engaged. In order to charge the
firearm the safety lever must be disengaged, resulting in the
trigger not being locked during charging. This presents another
potential safety issue.
[0010] The basic design of the AK-47 rifle described above also
pertains to other popular gas operated firearms, such as the
various Kalashnikov variants (AK-74, AK-101, AK-103, and others),
the Samozaryadniy Karabin sistemi Simonova (SKS) rifle and its
variants, and the Fusil Automatique Leger-Light Automatic Rifle
(FN-FAL) and its variants, as well as other designs. In this
respect, to the extent the deficiencies described above also apply
to these other gas operated firearms, the remediation which is
addressed by the present invention applies to these firearms as
well.
[0011] There thus remains a need for an improved charging mechanism
for a gas operated firearm that is more efficiently actuable for
right-handed operators, improves the safety profile of the firearm,
provides for easier inspection and cleaning, is simple and cost
effective to manufacture and which readily retrofits into existing
firearms.
SUMMARY
[0012] An aspect of the present invention discloses repositioning
of the charging handle of a gas operated firearm to the left side
of the firearm, further forward than the standard positioning of
the charging handle. This accomplishes two purposes. First, by
positioning the charging handle on the left side of the firearm, a
right-handed operator need not reach around over the top or
underneath the firearm with the left hand to reach the charging
handle. Rather, the charging handle is proximate to the left hand,
allowing for easier and quicker grasping of same. Second, by
positioning the charging handle further forward on the firearm, the
charging handle is closer to the operator's left hand when it is
supporting the barrel, allowing for a smoother transition of the
left hand from barrel to charging handle, reducing barrel movement
and loss of sight picture.
[0013] Another aspect of the present invention is to form into the
left side of a standard gas tube a lateral aperture running along
the longitudinal axis of the gas tube. The forward edge of the
aperture is located rearward of the forward portion of the gas
piston, such that the forward portion of the gas piston remains in
a closed portion of the gas tube when the gas piston is in the
forward position. The aperture allows access into the gas tube and
access to the shaft of the gas piston. As such, when the bolt
assembly is drawn rearward, the breach may be visually inspected
through the lateral aperture to determine whether there is a round
in the firing chamber. In addition, when the bolt assembly is drawn
rearward the forward portion of the gas tube, the bore, and the
chamber become accessible, allowing for cleaning of those portions
of the firearm without need for further disassembly. Access to the
inside of the gas tube through the aperture also acts as a means
for faster cooling of the firearm, as now outside air can circulate
inside the gas tube. This improves operation of the firearm, which
tends to build up heat from the friction of the bullets moving
along the barrel and the heat from the discharge gases after a
substantial amount of ammunition is fired. It also allows for more
efficient venting of the discharge gases after they have
accomplished the task of moving the gas piston rearward. As the
forward portion of the gas piston moves rearward past the front
edge of the lateral aperture, the gases escape through the lateral
aperture. This eliminates the need for a specially configured
discharge configuration to vent the gases from the firearm.
[0014] Another aspect of the present invention is to introduce a
semi-cylindrical sleeve onto the shaft of the gas piston. The
sleeve provides an attachment for the charging handle, which
extends through the lateral aperture of the gas tube. The rear
portion of the sleeve impinges against the rear portion of the gas
piston, such that when the sleeve is moved rearward, the gas
piston, and the bolt assembly in connection therewith, are moved
rearward with it. The combination of the lateral aperture formed
into the left side of the gas tube, the sleeve fitted over the
shaft of the gas piston, and the charging handle attached to the
sleeve and extending from the left side of the firearm represent
the basic configuration of the improved charging mechanism. This
basic configuration may be easily retrofitted to existing firearms
by simply substituting the modified gas tube for a standard gas
tube and adding the sleeve and charging handle. The present
invention contemplates such a conversion kit for retrofitting
firearms, comprising the modified gas tube, the sleeve, and the
charging handle.
[0015] Another aspect of the present invention is to introduce a
locking bifurcated sleeve onto the shaft of a gas piston. The
sleeve is confrontable by a charging tube connected to a charging
handle which extends through a lateral aperture of the gas tube.
The rear portion of the sleeve impinges against the rear portion of
the gas piston, such that when the charging tube is moved
rearwardly, the gas piston and the bolt assembly in connection
therewith, are moved rearwardly as well. The combination of the
lateral aperture formed into the left side of the gas tube, the
locking sleeve fitted over the shaft of the gas piston, and the
charging tube confronting the sleeve during a charging cycle and
having a charging handle attached thereto, extending from the left
side of the firearm represent one embodiment of the improved
charging mechanism. This basic configuration may be easily
retrofitted to existing firearms by simply substituting the
modified gas tube for a standard gas tube and installing the
locking sleeve around the shaft of the gas piston and installing a
charging tube and handle within the modified gas tube. The present
invention contemplates such a conversion kit for retrofitting
firearms, comprising the modified gas tube, the locking sleeve, the
charging tube and charging handle.
[0016] Another aspect of the present invention is to introduce a
modified gas piston having a rearward cylindrical block machined
directly into the shaft in lieu of a locking bifurcated sleeve. The
cylindrical block is confrontable by a charging tube connected to a
charging handle which extends through a lateral aperture of the gas
tube much the same as the bifurcated sleeve. When the charging tube
is moved rearwardly by drawing on the charging handle, the charging
tube confronts the cylindrical block of the gas piston and thus it
and the bolt assembly in connection therewith, are moved rearwardly
as well. The combination of the lateral aperture formed into the
left side of the gas tube, the modified shaft of the gas piston
having a cylindrical block, and the charging tube configured to
confront the cylindrical block during a charging cycle and having a
charging handle attached thereto, extending from the left side of
the firearm represent another embodiment of the improved charging
mechanism. This basic configuration may be easily retrofitted to
existing firearms by simply substituting the modified gas tube for
a standard gas tube and installing the modified gas piston with
cylindrical block and installing a charging tube and handle within
the modified gas tube. The present invention contemplates such a
conversion kit for retrofitting firearms, comprising the modified
gas tube, the modified gas tube, the charging tube and charging
handle.
[0017] In addition to the basic aspects of the present invention
described above, another aspect of the present invention is to form
a notch into the lateral aperture proximate to the rear edge of the
aperture, with the notch configured to receive and hold the shaft
of the charging handle. When the charging handle is moved rearward,
as it becomes aligned with the notch the charging handle may be
rotated upward such that its shaft fits into the notch. The notch
then holds the charging handle in place, under tension by the
recoil spring mechanism. This results in effectively holding the
gas piston and the bolt assembly in place in the open breach
position. The charging handle is able to rotate upwards due to the
semi-cylindrical configuration of the sleeve, which is free to
rotate about the shaft of the gas piston. So designed, the notch
acts as a bolt lock. The bolt lock serves as an additional safety
mechanism, as the firearm cannot fire a round when the bolt is
locked in the open breach position. It also improves safety by
allowing a visual inspection of the breach to see whether there is
a round chambered therein (which could occur even if the ammunition
magazine is empty or removed from the firearm). By locking the bolt
in the open breach position, the forward portion of the gas tube,
the bore, and the chamber can be easily cleaned through the lateral
aperture, as described above. The bolt lock is released by rotating
the charging handle shaft downward and out of the notch, so that it
rides within the lateral aperture. Releasing the charging handle
from the notch causes the recoil spring mechanism to force the bolt
assembly, the gas piston, and the charging handle forward,
resulting in the breach closing. The bolt lock can be easily
released with just the thumb of the left hand, thereby allowing the
firearm to be charged without removing the left hand from the
barrel, minimizing barrel movement and loss of sight picture.
[0018] Another aspect of the present invention is to allow the
charging handle to fold forward, out of the way when not in use.
Another aspect of the present invention contemplates the removal of
the standard right side charging handle, thereby freeing the bolt
assembly to move rearward even when the safety lever is engaged.
Thus, the firearm can have its safety lever engaged with the
trigger locked while the operator chambers a round. No longer is it
required for the safety to be disengaged in order to chamber a
round. When the operator is ready to fire, the safety can be
disengaged. These aspects further improve the safety profile of the
firearm.
[0019] The improved charging mechanism allows a right-handed
operator to charge the firearm more easily. He or she no longer has
to reach over or under to charge the rifle. The charging handle is
now in a convenient location, proximate to the position where the
operator must place the left hand while firing. This allows not
only faster reloading then the existing configuration, but safer
reloading. The operator no long has to worry about losing sight
picture or unbalancing the firearm when charging the firearm. The
charging handle is also in an improved location for carrying the
firearm when it is slung across the chest by a sling strap. By
being located further forward on the firearm, the charging handle
is no longer in a spot where it may harm the operator if the
firearm is forced into the chest, for example if the operator falls
onto the firearm while carrying it by its sling.
[0020] The present invention also contemplates a method of
retrofitting gas operated firearms to use the improved charging
mechanism disclosed herein. The method includes the steps of
obtaining a modified gas tube as disclosed above; obtaining a
sleeve as disclosed above; obtaining a modified charging handle as
disclosed above; disassembling the firearm, at least to the extent
of removing the original gas tube and the gas piston; placing the
sleeve over the shaft of the gas piston; reassembling the firearm,
whereby the modified gas tube is substituted for the original gas
tube and the gas piston with the sleeve placed over its shaft is
inserted into the modified gas tube; and attaching the modified
charging handle to the sleeve, with the optional step of removing
the original charging handle from the right side of the
firearm.
[0021] It is therefore an object of an aspect of the invention to
provide an improved charging mechanism for a gas operated firearm
which adds safety features to the firearm.
[0022] It is a further object of an aspect of the invention to
provide an improved charging mechanism for a gas operated firearm
which is easier to use for right-handed operators.
[0023] It is yet a further object of an aspect of the invention to
provide an improved charging mechanism for a gas operated firearm
that is easy to clean and maintain.
[0024] It is yet a further object of an aspect of the invention to
provide an improved charging mechanism for a gas operated firearm
which is easy to manufacture.
[0025] It is yet a further object of an aspect of the invention to
provide an improved charging mechanism for a gas operated firearm
which is easy to retrofit to an existing firearm.
[0026] It is yet a further object of an aspect of the invention to
provide an improved charging mechanism for a gas operated firearm
which allows for faster loading and more accurate operation of the
firearm.
[0027] It is yet a further object of an aspect of the invention to
provide an improved charging mechanism for a gas operated firearm
that improves the durability of the firearm by reducing harmful
heat buildup.
[0028] It is yet a further object of an aspect of the invention to
provide a method for retrofitting a gas operated firearm with an
improved charging mechanism.
[0029] Other objects of this invention will be apparent to those
skilled in the art from the description and claims which
follow.
DESCRIPTION OF DRAWINGS
[0030] FIG. 1 is a side view of the right side of a prior art
charging mechanism for a gas operated firearm. The gas piston is
shown within the gas tube in phantom lines. A cutaway of the barrel
exposes the gas port;
[0031] FIG. 2 is a partial side view of the left side of a prior
art charging mechanism for a gas operated firearm. A cutaway of the
barrel exposes the gas port;
[0032] FIG. 3 is a top view of a prior art charging mechanism for a
gas operated firearm. The gas piston is shown within the gas tube
in phantom lines. A cutaway of the barrel exposes the gas port;
[0033] FIG. 4 is a partial side view of the left side of one aspect
of an embodiment of the present invention. A cutaway of the barrel
exposes the gas port;
[0034] FIG. 5 is a side view of the gas piston, bolt assembly, and
recoil spring mechanism of one aspect of an embodiment of the
present invention, with the sleeve placed over the shaft of the gas
piston, which is shown in phantom;
[0035] FIG. 6 is a rear cutaway view of the gas tube, sleeve, and
gas piston shown in FIG. 5 taken through section A-A;
[0036] FIG. 7 is a partial side view of the left side of one aspect
of an embodiment of the present invention with the charging handle
drawn back and rotated into the notch, depicting the gas piston in
a rearward position with the interior of the gas tube exposed;
[0037] FIG. 8 is a perspective partial side view of the left side
of one aspect of an embodiment of the present invention with the
charging handle drawn back and rotated into a cocking notch wherein
the weapon is maintained in an open bolt condition and depicting
the interior of the gas tube exposed. A cutaway of the barrel
exposes the gas port;
[0038] FIG. 9 is a partial top view of one aspect of an embodiment
of the present invention depicting an alternative embodiment of the
charging handle, with phantom lines showing the direction of hinged
motion and the folded position of the gripping member of the
charging handle;
[0039] FIG. 10A is a partial side view of the left side of one
aspect of an embodiment of the present invention depicting another
alternative embodiment of the charging handle, with phantom lines
showing the direction of pivoting motion and the forward position
of the gripping member of the charging handle;
[0040] FIG. 10B is a rear cutaway view of the gas tube, sleeve, and
gas piston of the embodiment shown in FIG. 10A taken through
section B-B;
[0041] FIG. 11 is a side view of one aspect of an embodiment of the
present invention depicting the modified gas tube, the sleeve, and
one embodiment of the modified charging handle;
[0042] FIG. 12 is a rear cutaway view of one aspect of an
embodiment of the present invention depicting the sleeve and
another embodiment of the modified charging handle;
[0043] FIG. 13 is a perspective view of one aspect of an embodiment
of the present invention depicting a modified gas tube, a charging
handle and tube, bifurcated sleeve members and a locking
bushing;
[0044] FIG. 14 is a perspective view of one aspect of an embodiment
of the present invention depicting a modified gas tube, charging
components within the gas tube and a sight rail located atop of the
gas tube;
[0045] FIG. 15 is a perspective view of an aspect of one embodiment
of the present invention depicting the shaft of the gas piston of a
firearm being engaged by bifurcated sleeve members and locking
bushing, in mating alignment with the charging tube;
[0046] FIG. 16 is a perspective view of an aspect of one embodiment
of the present invention depicting modified gas piston of a firearm
including a cylindrical block, in mating alignment with the
charging tube;
[0047] FIG. 17 is a perspective view of an AK-47 style weapon with
its dust cover and recoil spring assembly removed, a locked
bifurcated sleeve mounted around the shaft of the gas piston,
oriented to be inserted into the receiver and modified gas tube in
accordance with an aspect of one embodiment of the present
invention; and
[0048] FIG. 18 is a partial elevational view of an AK-47 style
weapon having a modified gas tube and charging system according to
an embodiment of the present invention with the charging handle
retained by the cocking notch in a locked, open bolt condition.
DETAILED DESCRIPTION
[0049] Referring to FIGS. 1-3, a representative AK-47 style weapon
according to the art is there disclosed. The present invention is
intended to modify a gas operated firearm 1 having at least the
following components: a barrel 10, a receiver 22, a trigger 90, a
firing chamber 30, a bolt assembly 40, a recoil spring assembly 50,
a gas piston 300, an ammunition magazine 60, a port 70 formed into
the barrel 10, a gas block 100, a gas tube 34, and a charging
handle 32. See The firearm 1 may also comprise a pistol grip 20,
butt stock 24 (see FIG. 16) and a safety 80.
[0050] In operation, the bolt assembly 40 of the firearm 1 is
suitably adapted to reciprocated between forward and rearward
positions, with its rearward movement causing a round of ammunition
to be moved into the firing chamber 30 and its forward movement
aligning the firing mechanism of the firearm 1 to permit firing of
the round of ammunition. The movement of a round of ammunition into
the firing chamber 30 and readying it for firing is known as
charging the firearm 1. The gas piston 300 of the firearm 1 is
located within the gas tube 34 and is suitably adapted to
reciprocate forward and rearward within the gas tube. Being further
in connection with the front portion 42 of the bolt assembly 40 the
gas piston 300 in cooperation with bolt carrier 46 is suitably
adapted to move the bolt assembly 40 in a rearward direction. See
FIGS. 3 and 5. The gas piston 300 is rigid and substantially
cylindrical, having a forward portion 302, a rear portion 304, and
a shaft 310 interposed between the forward portion and the rear
portion, with the outside diameter of the shaft 310 less than the
outside diameter of either the forward portion 302 or the rear
portion 304 of the gas piston 300. The recoil spring mechanism 50
of the firearm 1 is in connection with the bolt carrier 46 and is
suitably adapted to bias the bolt assembly 40 in a forward
direction upon being compressed when the bolt assembly is moved in
a rearward direction. The ammunition magazine 60 has a spring
loading mechanism suitably adapted to move a round of ammunition
upward and ready to be stripped from the magazine by the forward
motion of the bolt and directed into the firing chamber 30 of the
firearm 1 when the bolt assembly has been released from its
rearward position.
[0051] The port 70 formed into the barrel 10 of the firearm 1
provides a communication between the barrel 10 and the gas tube 34
via the gas block 100, through which a portion of the gas generated
by the firing of a round of ammunition may pass. This discharge gas
passing out of the barrel 10 through the port 70 and gas block 100
into the gas tube 34 exerts a pressure against the forward portion
302 of the gas piston 300 urging it rearward, thereby
simultaneously moving the bolt carrier 46 rearward. The movement of
the bolt carrier 46 rearward by the gas piston 300, followed by the
forward movement of the bolt assembly 40 by the recoil spring
mechanism 50, constitutes an automatic charging cycle of the
firearm 1 by gas operation. Alternatively, the charging handle 32
may be used by the operator to manually draw the bolt carrier 46
rearward, constituting a manual charging cycle. A manual charging
cycle is necessary to prepare the firearm 1 for firing a round of
ammunition upon reloading or in the event of a misfire or
misfeed.
[0052] Variations on the specifics of the foregoing basic firearm
components may be found, but the described functionality should be
present. Examples of firearms having these basic components are the
Kalashnikov (AK-47) rifle and its variants, the Kalashnikov (AK-74)
rifle and its variants, the Kalashnikov (AK-101) rifle and its
variants, the Kalashnikov (AK-103) rifle and its variants, the
Samozaryadniy Karabin sistemi Simonova-style (SKS) rifle, and the
Fusil Automatique Leger-Light Automatic Rifle (FN-FAL) rifle. The
present invention may be used to retrofit other similarly
configured gas operated firearms.
[0053] Referring to FIG. 4, the improved charging mechanism of one
embodiment of the present invention comprises a modified gas tube
200, a sleeve 500, and a modified charging handle 400. The modified
gas tube 200 is in communication with the gas block 100 such that a
portion of the gas created from the firing of a round of ammunition
is discharged from the barrel 10 through port 70, through the gas
block 100 and into the modified gas tube 200 to impinge upon the
front face portion 302 of gas piston 300. The modified gas tube 200
has a substantially cylindrically shaped interior 210 with a
substantially constant inside diameter which is sized to be
slightly greater that the diameter of the face portion 302 of the
gas piston 300. The modified gas tube 200 of the present invention
is suitably adapted to accommodate within its interior 210 the gas
piston 300, which reciprocates forward and rearward within the
modified gas tube 200. The inside diameter of the modified gas tube
200 should be substantially the same as, but just slightly less
than, the outside diameter of the forward portion 302 of the gas
piston 300. A snug fit between the forward portion 302 of the gas
piston 300 and the modified gas tube 200 minimizes the potential
for discharge gases entering the gas tube from the gas block 100 to
leak around the forward portion of the gas piston, thereby
maximizing the force of the discharge gases against the forward
portion of the gas piston. The inside surface of modified gas tube
200 and the outside surface of the forward portion 302 of the gas
piston 300 may be polished or otherwise treated, such as with a
lubricant, to minimize friction between the two mated surfaces.
[0054] The modified gas tube 200 further has a lateral aperture 220
formed along the majority of its left side, passing completely
through the modified gas tube into its interior 210. See FIG. 4.
The lateral aperture 220 runs parallel to the longitudinal axis of
the modified gas tube 200 and has substantially parallel top and
bottom edges 226, 228. The lateral aperture 220 provides access
into the modified gas tube 200 of the present invention. This
access allows cleaning of the forward portions of the modified gas
tube 200 without disassembly of the firearm 1. In the preferred
embodiment of the present invention, the front edge 222 of the
lateral aperture 220 is located rearward of the location of the
forward portion 302 of the gas piston 300 when the gas piston is in
a forward position within the modified gas tube 200. That is, the
lateral aperture 220 is located behind the forward portion 302 of
the gas piston 300 when it is in the forward position. This
prevents discharged gas from escaping from the modified gas tube
200 through the lateral aperture 220 when the gas piston 300 is in
the forward position. As gas exerts a pressure on the forward
portion 302 on the gas piston 300, urging it rearward, the forward
portion of the gas piston moves alongside the lateral aperture 220
exposing the interior 210 of the modified gas tube 200, thereby
allowing the gases to vent from the modified gas tube through the
lateral aperture.
[0055] In one embodiment of the present invention the lateral
aperture 220 of the modified gas tube 200 may be centered on the
left side of the modified gas tube substantially midway between the
top and the bottom of the modified gas tube (i.e., within a
horizontal plane passing through the center of the modified gas
tube). In another embodiment the lateral aperture 220 may be
centered somewhat higher than the horizontal to the modified gas
tube 200. In the preferred embodiment the lateral aperture 220 is
centered not more than forty-five degrees) (45.degree.) above the
horizontal. See FIG. 6.
[0056] The lateral aperture 220 of the modified gas tube 200 may
further comprise a notch 230, the notch being formed into the
lateral aperture 220 along its top edge 226, proximate to its rear
edge 224, thereby causing the lateral aperture to have an inverted
"T" configuration. See FIG. 4. The notch 230 has a width suitably
adapted to receive and retain the modified charging handle 400 of
the present invention and place the host firearm in a bolt open
condition. See FIGS. 4, 7, and 8.
[0057] The sleeve 500 of one embodiment of the present invention is
arcuate in a substantially semi-cylindrical configuration, allowing
the sleeve 500 to be placed onto the shaft 310 of the gas piston
300 within the modified gas tube 200. See FIGS. 6 and 11. As such,
the sleeve 500 has an outside diameter substantially the same as
but not greater than the inside diameter of the modified gas tube
200. The inside surface of the modified gas tube 200 and the
outside surface of the sleeve 500 may be polished or otherwise
treated, such as with a lubricant, to minimize friction between the
two mated surfaces. The inside diameter of the sleeve 500 is
substantially the same as but not less than the outside diameter of
the shaft 310 of the gas piston 300. The length of the sleeve 500
is substantially the same as, but not longer than, the length of
the shaft 310 of the gas piston 300, thereby allowing it to nest
with the shaft of the gas piston. See FIGS. 5 and 6. In alternate
embodiments of the present invention the arc of the outer surface
of the sleeve 500 may be significantly less than one hundred eighty
degrees) (180.degree.), though preferably more than ninety degrees)
(90.degree.). The dimensions of the sleeve 500 are configured so
that the gas piston 300, when the sleeve 500 is placed onto its
shaft 310, will continue to fit into the modified gas tube 200 and
reciprocate forward and rearward within the modified gas tube along
with the gas piston. The sleeve 500 may rotate about the shaft 310
of the gas piston 300 when it is placed thereon. Because the rear
portion 304 of the gas piston 300 has an outside diameter greater
than the outside diameter of the shaft 310 of the gas piston 300,
the rear portion 504 of the sleeve 500 will impinge against the
front of the rear portion of the gas piston when the sleeve is
placed onto the shaft of the gas piston and moved rearward. See
FIG. 5. Movement of the sleeve 500 rearward therefore exerts
pressure on the rear portion 304 of the gas piston 300 and moves
the gas piston rearward.
[0058] The charging handle 400 of the present invention is suitably
adapted to be attached to the sleeve 500, such that the charging
handle extends from the sleeve through the lateral aperture 220 of
the modified gas tube 200 from the left side of the firearm 1 when
the sleeve is placed onto the shaft 310 of the gas piston 300 and
the gas piston is placed within the modified gas tube. In one
embodiment of the present invention, the charging handle 400 is
attached to the sleeve 500 proximate to its forward end 502. See
FIG. 5. In one embodiment of the present disclosure, the charging
handle 400 is removably attached to the sleeve 500. The operator of
the firearm 1 may draw the charging handle 400 rearward, which
simultaneously moves the sleeve 500 rearward, effecting rearward
pressure upon the rear portion 304 of the gas piston 300 and
thereby moving the gas piston and the bolt carrier 46 rearward,
thus initiating a manual charging cycle. After the bolt carrier 46
is drawn to the rear of the firearm 1, release of the charging
handle 400 results in the recoil spring mechanism 50 urging the
bolt carrier forward, stripping the next round of ammunition from
the magazine 60 and feeding it into the firing chamber 30, while
simultaneously moving the gas piston 300, the sleeve 500, and the
charging handle forward, thus completing the manual charging
cycle.
[0059] In embodiments of the present invention utilizing a cocking
notch 230 formed into the lateral aperture 220, the notch is
configured to be located rearward of the position of the charging
handle 400 when the bolt carrier 46 is in its forward position. See
FIG. 4. In such configurations, the charging handle 400 may be
directed into the notch 230 by the operator as they draw the
charging handle back until it is aligned with the notch and then
moving the charging handle upward into the notch. See FIGS. 7, 8
and 18. The charging handle 400 is capable of being moved into
cocking notch 230 because the sleeve 500 to which it is attached is
capable of rotating about the shaft 310 of the gas piston 300. The
recoil spring mechanism 50 exerts a force against the bolt carrier
46, which translates to the gas piston 300, the sleeve 500, and the
charging handle 400, biasing the charging handle within cocking
notch 230. In this configuration the notch 230 acts as a bolt open
lock. The bolt carrier 46 and bolt assembly 40 are held in an open
position and cannot be moved until the charging handle 400 removed
from the cocking notch 230. The bolt lock therefore acts as an
alternative safety mechanism. It also acts as a means for
maintaining access to the firing chamber 30 through the lateral
aperture 220 for cleaning purposes.
[0060] In one embodiment of the present invention the charging
handle 400 comprises a shaft 410, whereby the shaft of the charging
handle is suitably adapted to connect the charging handle to the
sleeve 500. In one embodiment the shaft 410 of the charging handle
400 comprises threads 412 formed thereon and the sleeve 500
comprises a threaded aperture 516 formed therein, with the threaded
aperture 516 of the sleeve suitably adapted to accommodate the
threads formed onto the shaft of the charging handle. See FIG. 11.
In this embodiment, the charging handle 400 is connected to the
sleeve 500 by screwing the threaded shaft 410 of the charging
handle into the threaded aperture 516 of the sleeve. In an
alternate embodiment the sleeve 500 comprises a pin 510 extending
laterally therefrom, with the pin having threads 512 formed
thereupon. The shaft 410 of the charging handle 400 comprises an
end 414 and a threaded aperture 416 formed into the end of the
shaft of the charging handle, with the threaded aperture suitably
adapted to accommodate the threads 512 formed onto the shaft of
said pin 510. See FIG. 12. The charging handle 400 is thus
connected to the sleeve 500 by screwing the threaded aperture 416
in the end 414 of the charging handle \ onto the threaded pin 510
of the sleeve. Other known configurations for removably attaching
the shaft 410 of the charging handle 400 to the sleeve 500 are also
contemplated by the present invention.
[0061] In the embodiments of the present invention in which the
charging handle 400 comprises a shaft 410 and the modified gas tube
200 comprises a cocking notch 230, the width of the notch is
suitably adapted to receive and retain the shaft of the charging
handle. In other embodiments of the present invention the charging
handle 400 comprises a gripping member 420 and a pivot mechanism
430, with the gripping member oriented substantially perpendicular
to the shaft 410 of the charging handle. See FIGS. 10A and 10B. The
pivot mechanism 430 connects the gripping member 420 to the shaft
410 of the charging handle 400, such that the pivot mechanism
permits the gripping member of the charging handle to be rotated
forward toward the front of the firearm 1 in a substantially
horizontal orientation and rotated rearward to extend substantially
vertically. In yet other embodiments of the present invention the
charging handle 400 comprises a gripping member 420 and a hinge
mechanism 440, with the hinge mechanism suitably adapted to permit
the gripping member of the charging handle to be folded forward
toward the firearm 1 and unfolded to extend substantially
perpendicularly from the firearm 1. In the embodiments of the
present invention that utilize a reciprocating charging handle 400,
it is desirable to pivot the gripping member 420 of the charging
handle parallel to the modified gas tube 200, thus reducing the
risk of the operator coming into inadvertent contact with the
reciprocating charging handle. See FIG. 9. In yet other embodiments
of the present invention the charging handle 400 is angled to
provide a more comfortable grip for the operator's hand. Other
configurations of the reciprocating charging handle 400 are also
contemplated.
[0062] One aspect of the present invention also contemplates a
method of retrofitting a gas operated firearm 1. The firearm 1
comprises a barrel 10, a receiver 22, a firing chamber 30, a bolt
assembly 40 within a bolt carrier 46, a recoil spring mechanism 50
in connection with a rear portion 44 of the bolt carrier, a right
side charging handle 32 extending from the front of the bolt
carrier, a gas piston 34 in connection with a front portion 42 of
the bolt assembly 40, an ammunition magazine 60 having a spring
loading mechanism, a port 70 formed into the barrel 10 providing a
communication between the barrel 10 and a gas block 100, and a
closed gas tube in connection with the gas block 100, all as
described above.
[0063] The method of retrofitting the gas operated firearm 1
comprises the steps:
[0064] A. obtaining a modified gas tube 200 having the
characteristics and functions described above, see FIG. 11;
[0065] B. obtaining a sleeve 500 having the characteristics and
functions described above, see FIG. 11;
[0066] C. obtaining a modified charging handle 400 having the
characteristics and functions described above, see FIG. 11;
[0067] D. disassembling the firearm 1, at least to the extent of
removing the closed gas tube and the gas piston 300;
[0068] E. placing the sleeve 500 over the shaft 310 of the gas
piston 300;
[0069] F. reassembling the firearm 1, whereby the modified gas tube
200 is substituted for the closed gas tube 34 and the gas piston
300 with the sleeve 500 placed over its shaft 310 is inserted into
the modified gas tube 200; and
[0070] G. attaching the modified charging handle 400 to the sleeve
500.
[0071] Steps A-D of the method may be performed in any order, step
E may be performed any time after steps B and D and before step F,
step F may be performed any time after steps A, B, D, and E, and
step G may be performed any time after steps B and C.
[0072] In an alternative method, the optional step H may be
performed at any time relative to steps A-G, with step H involving
removing the right side charging handle 32 from the firearm 1.
[0073] Referring now to FIGS. 13-18, additional embodiments of the
present invention are disclosed. Unlike the previously disclosed
embodiments, in each of the embodiments therein disclosed, the
modified charging handle 1400 does NOT reciprocate along with the
gas operation of the weapon, an often desirable feature. In this
regard, the operator is not exposed to external moving parts, such
as the charging handle 400 which does reciprocate with the firing
of the host weapon at whatever rate of fire being employed.
[0074] Modified gas tube 1200 is provided having a lateral aperture
1220 running along its left side. Lateral aperture 1220 is
configured to allow charging handle 1400, which is affixed to
charging tube 1500, to extend through the left side of the modified
gas tube 1220 when it is in the forward position. A detent may be
provided near the front of lateral aperture 1220 for retaining
charging handle 1400 in a passive position when not being manually
actuated. A cocking notch 1230 may be provided near the upper rear
of the lateral aperture for locking charging handle 1400 in a bolt
open condition. A sight rail 1600 may be provided atop modified gas
tube 1200 and configured in any number of common arrangements, such
as the MIL-STD-1913 rail, STANAG 2324 rail, or simply referred to
as a "Tactical Rail" standardized mounting platform, as generally
depicted in FIG. 14. The sight rail 1600 may be affixed to modified
gas tube 1200 in any number of ways, including without limitation,
screws, welds, adhesive, tongue and grove, or otherwise machined as
a unitary portion of the modified gas tube itself. Components of
the gas piston sleeve assembly 1304 may be fabricated from any
durable material suited for the application, including without
limitation, hardened steel, type 4140, stainless steel, and
finished in one of several ways including, without limitation,
nitrite and chromium.
[0075] Bifurcated sleeve members 1300a and 1300b are provided and
are configured having an inside diameter, when assembled and held
in place with locking bushing 1302, to fit snugly about the shaft
310 of gas tube 300. When locking bushing 1302 is coupled to
bifurcated sleeve members 1300a and 1300b, it forms an integrated
gas tube sleeve assembly 1304. Once assembled on the shaft 310 of
gas tube 300, it may be secured into its rearmost position using
any number of common fastening means (not shown), such as a drive
pin or set screw, or may be welded or fixed into place with
adhesive. The forward edge of locking bushing 1302 is configured to
have substantially the same diameter as charging tube 1500. Thus
when the charging handle 1400 is drawn toward the rear of the
weapon 1, the charging tube 1500 to which it is connected, travels
rearward as well and its rearmost face abuts against the foremost
face of the locking bushing 1302 portion of the gas piston sleeve
assembly 1304, thus urging the bolt carrier 46 and each of its
corresponding components toward the rear of the weapon. In this
manner the weapon 1 becomes manually charged. If it is desired to
keep the bolt open after charging, charging handle 1400 is directed
into cocking notch 1230 where it will retain the bolt in an open
condition until released.
[0076] Looking now to FIG. 16, an alternate embodiment of the
present invention is therein disclosed. This embodiment is similar
to that shown in FIG. 15, except that in this arrangement the gas
piston sleeve assembly 1304 is replaced by a cylindrical block 1322
which may be machined as part of a modified gas piston 1320. Like
the arrangement shown in FIG. 15, this configuration uses the rear
face of charging handle 1500 to engage the leading face of the
cylindrical block 1322 to urge bolt carrier 46 rearward when the
charging handle 1400 is drawn rearwardly. While this embodiment may
be less desirable to some because more components of the host
weapon 1 are affected, namely the gas piston 300 which is replaced
with modified gas piston 1322, the arrangement has the advantage of
fewer component parts (3 versus 5) than previously discussed. The
fewer the number of components the easier installation and the
fewer components that can fail. As with each of the embodiments of
the present invention, this one contemplates being utilized to
retrofit into existing firearms 1 in order to provide the operator
with a faster, less cumbersome and more accurate charging
system.
[0077] What has been described and illustrated herein is a
preferred embodiment of the invention along with some it its
variations. The terms, descriptions and figures used herein are set
forth by way of illustration only and are not meant as limitations.
Those skilled in the art will recognize that many variations are
possible within the spirit and scope of the invention as defined in
the following claims in which all terms are meant in their
broadest, reasonable sense unless otherwise indicated.
* * * * *