U.S. patent application number 11/810790 was filed with the patent office on 2011-02-03 for firearm with gas system accessory latch.
Invention is credited to Christopher Gene Barrett.
Application Number | 20110023699 11/810790 |
Document ID | / |
Family ID | 43525755 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110023699 |
Kind Code |
A1 |
Barrett; Christopher Gene |
February 3, 2011 |
FIREARM WITH GAS SYSTEM ACCESSORY LATCH
Abstract
A gas-operated firearm has a barrel defining a bore with a gas
block defining a chamber communicating with the bore via a gas
passage. A gas regulation element has a first position and a second
position, and serves to provide different gas flow characteristics
in the different positions. The latch element gives the user
audible or tactile feedback upon installation of an accessory
device when the gas regulation element is a correct position suited
to use of the accessory, and not when in the other position
unsuited to accessory usage. The accessory may be a sound
suppressor, and the latch may serve to secure the gas regulation
element against position change. The latch may engage a circular
array of elements on the rear face of the suppressor, and may have
an angled cam face to provide ratcheting engagement for
installation, and to resist removal or loosening without deliberate
actuation of the latch.
Inventors: |
Barrett; Christopher Gene;
(Murfreesboro, TN) |
Correspondence
Address: |
LANGLOTZ PATENT & TRADEMARK WORKS, INC.
PO BOX 96503 #37585
Washington
DC
20090-6503
US
|
Family ID: |
43525755 |
Appl. No.: |
11/810790 |
Filed: |
June 6, 2007 |
Current U.S.
Class: |
89/193 |
Current CPC
Class: |
F41A 5/28 20130101 |
Class at
Publication: |
89/193 |
International
Class: |
F41A 5/28 20060101
F41A005/28; F41A 21/30 20060101 F41A021/30 |
Claims
1. A firearm comprising; a body; a bolt assembly reciprocating
within the body; a barrel defining a bore and extending from the
body; a gas block defining a chamber and connected to the barrel;
the gas block and barrel defining a first gas passage communicating
between the barrel bore and the gas block chamber; the gas block
defining a second gas passage communicating between the gas block
chamber and an atmosphere outside of the gas block. a gas
regulation element having a first position and a second position,
the regulation element operable to constrict at least one of the
first and second gas passages by different amounts in the first and
second positions; and the gas regulation element including a latch
element operable to engage an accessory device mounted to the
firearm when the gas regulation element is in the first position,
and operable to remain disengaged from the accessory device mounted
to the firearm when the gas regulation element is in the second
position: and wherein the accessory device is a sound
suppressor.
2. (canceled)
3. The firearm of claim I wherein the accessory device is mounted
to a muzzle end of the barrel.
4. The firearm of claim 1 wherein the latch element is operable to
provide tactile feedback in response to installation of the
accessory device when the gas regulation element is in the first
position.
5. The firearm of claim I wherein the latch element is operable to
prevent unintended loosening and removal of the accessory device
when in the first position.
6. The firearm of claim 1 wherein the accessory device is
threadably attached to the firearm.
7. The firearm of claim 1 wherein the accessory device includes an
annular array of engagement elements operable to engage the latch
as the accessory device is rotationally connected to the
firearm.
8. The firearm of claim 1 wherein the latch reciprocates along an
axis, has a cam surface angled to the axis and operable to contact
engagement elements on the accessory device.
9. The firearm of claim 1 wherein the latch is a spring loaded
element that biased into engagement with the accessory device.
10. The firearm of claim 1 wherein the latch element in the first
position operates to permit installation of the accessory device
while giving tactile feedback during installation, and to secure
the installed accessory device against unintended loosening and
removal.
11. The firearm of claim 1 wherein the latch element reciprocates
on a latch axis parallel to the bore, and where the gas regulation
element has a first passage positioned to register with the latch
axis and to permit the latch element to protrude beyond the
regulation element when the regulation element is in the first
position, and a blocking element sized and to prevent the latch
element from protruding beyond the regulation element.
12. The firearm of claim 11 including a second passage positioned
to register with the latch axis when the regulation element is in
the second position, and sized to receive the latch element, the
blocking element being an end portion of the second passage.
13. The firearm of claim 1 wherein the latch element engages the
gas regulation element to secure the regulation element in a
rotational position against unintended rotation.
14. The firearm of claim 1 wherein the accessory device mounted to
the firearm is a sound suppressor comprising: a body defining a
bore axis; an attachment element providing engagement to a firearm
by rotation of the body on the bore axis; an annular array of
engagement elements encircling the bore axis operable to engage a
latch on the firearm to secure the suppressor against inadvertent
loosening and removal.
15. The firearm of claim 14 wherein the body is a cylinder having a
rear face, and wherein the engagement elements are on the rear
face.
16. The firearm of claim 14 wherein each engagement element has a
cam surface angled with respect to the bore axis, such that the cam
surfaces will engage and bypass the latch upon rotational
installation of the suppressor on the firearm.
17. The firearm of claim 14 wherein the engagement elements and the
latch element cooperate to provide ratcheting engagement to permit
suppressor attachment and prevent suppressor removal without manual
actuation of the latch.
18. The firearm of claim 1 wherein the gas regulation element is
operable to provide different gas flow characteristics in each of
the first and second positions and the latch element is operable to
provide a user-detectable feedback upon installation of an
accessory device when the gas regulation element is in the first
position, and to refrain from providing the a user-detectable
feedback when the gas regulation element is in the second position,
such that the user receives the feedback when installing the
accessory device only when the gas regulation element is in a
position compatible with use of the accessory device.
19. The firearm of claim 18 wherein the latch element secures the
gas regulation element in a selected position.
20. The firearm of claim 18 wherein the feedback is selected from a
group of feedback types including audible and tactile feedback.
21. A firearm comprising; a body; a bolt assembly reciprocating
within the body; a barrel defining a bore and extending from the
body; a gas block defining a chamber and connected to the barrel;
the gas block and barrel defining a first gas passage communicating
between the barrel bore and the gas block chamber; the gas block
defining a second gas passage communicating between the gas block
chamber and an atmosphere outside of the gas block. a gas
regulation element having a first position and a second position,
the regulation element operable to constrict at least one of the
first and second gas passages by different amounts in the first and
second positions; the gas regulation element including a latch
element operable to engage an accessory device mounted to the
firearm when the gas regulation element is in the first position,
and operable to remain disengaged from the accessory device mounted
to the firearm when the gas regulation element is in the second
position; and wherein the latch reciprocates along an axis, has a
cam surface angled to the axis and operable to contact engagement
elements on the accessory device.
22. A firearm comprising; a body; a bolt assembly reciprocating
within the body; a barrel defining a bore and extending from the
body; a gas block defining a chamber and connected to the barrel;
the gas block and barrel defining a first gas passage communicating
between the barrel bore and the gas block chamber; the gas block
defining a second gas passage communicating between the gas block
chamber and an atmosphere outside of the gas block. a gas
regulation element having a first position and a second position,
the regulation element operable to constrict at least one of the
first and second gas passages by different amounts in the first and
second positions; the gas regulation element including a latch
element operable to engage an accessory device mounted to the
firearm when the gas regulation element is in the first position,
and operable to remain disengaged from the accessory device mounted
to the firearm when the gas regulation element is in the second
position; and wherein the latch element in the first position
operates to permit installation of the accessory device while
giving tactile feedback during installation, and to secure the
installed accessory device against unintended loosening and
removal.
23. A firearm comprising; a body; a bolt assembly reciprocating
within the body; a barrel defining a bore and extending from the
body; a gas block defining a chamber and connected to the barrel;
the gas block and barrel defining a first gas passage communicating
between the barrel bore and the gas block chamber, the gas block
defining a second gas passage communicating between the gas block
chamber and an atmosphere outside of the gas block. a gas
regulation element having a first position and a second position,
the regulation element operable to constrict at least one of the
first and second gas passages by different amounts in the first and
second positions; the gas regulation element including a latch
element operable to engage an accessory device mounted to the
firearm when the gas regulation element is in the first position,
and operable to remain disengaged from the accessory device mounted
to the firearm when the gas regulation element is in the second
position; and wherein the latch element reciprocates on a latch
axis parallel to the bore, and where the gas regulation element has
a first passage positioned to register with the latch axis and to
permit the latch element to protrude beyond the regulation element
when the regulation element is in the first position, and a
blocking element sized and to prevent the latch element from
protruding beyond the regulation element.
24. The firearm of claim 23 including a second passage positioned
to register with the latch axis when the regulation clement is in
the second position, and sized to receive the latch element, the
blocking element being an end portion of the second passage.
25. A firearm comprising; a body; a bolt assembly reciprocating
within the body; a barrel defining a bore and extending from the
body; a gas block defining a chamber and connected to the barrel;
the gas block and barrel defining a first gas passage communicating
between the barrel bore and the gas block chamber; the gas block
defining a second gas passage communicating between the gas block
chamber and an atmosphere outside of the gas block. a gas
regulation element having a first position and a second position,
the regulation element operable to constrict at least one of the
first and second gas passages by different amounts in the first and
second positions; the gas regulation element including a latch
element operable to engage an accessory device mounted to the
firearm when the gas regulation element is in the first position,
and operable to remain disengaged from the accessory device mounted
to the firearm when the gas regulation element is in the second
position; and wherein the latch element engages the gas regulation
element to secure the regulation element in a rotational position
against unintended rotation.
Description
FIELD OF THE INVENTION
[0001] This invention relates to firearms, and more particularly to
gas-operated self-loading firearms.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] Auto-loading rifles generally employ the energy produced in
firing a round to cycle a bolt (bolt carrier and bolt) and load the
next round. This includes machine guns and semi-automatic rifles of
many types.
[0003] One type of system for transferring energy to the bolt
employs the gas pressure developed behind the bullet in the barrel
upon discharge. This is know as a direct-gas operated system. A
small lateral vent hole is provided in the barrel (usually at a
forward location), and the momentary gas pressure is transmitted
through the vent hole back to the bolt assembly to cycle it. In
direct-gas-operated rifles (such as an M16 or M4 rifle) the gas
pressure is transmitted via a tube that extends back to the bolt,
which has a piston-like portion to which the gas imparts pressure.
In others (such as an M14) the gas pressure enters a cylindrical
chamber, where a piston connected via a rod transmits the force
back to the bolt assembly. This may either push the bolt assembly
so that the rod and bolt assembly initially move together, or the
rod may "tap" the bolt assembly, providing an impulse to move the
bolt assembly rearward in its cycle.
[0004] The degree of force generated by the gas pressure is desired
to remain in a selected range. Inadequate pressure can cause the
firearms to fail to fully cycle, thus failing to chamber a round.
Excessive pressure can cause excessive wear, and may damage
components, as well as causing unreliable performance. Therefore,
the aperture used to admit gas to the gas block from the barrel is
carefully sized based on engineering principles, as is the aperture
that allows gas from the gas block to vent to atmosphere. Each of
these affect operation.
[0005] In some firearms, several apertures of different sizes are
provided, with a rotating plug having the different sized
apertures, so that whichever aperture is positioned over the gas
passage from the barrel will determine the amount of gas admitted
to the gas block. This permits the use of ammunition with different
characteristics, and can compensate for powder fouling that can
occlude or reduce the effective diameter of an aperture, reducing
its gas transmission capability. In other versions, the variable
aperture principle is applied to the aperture that vents the gases
from the gas block, with a larger atmospheric vent aperture
diminishing the pressure and duration in the gas block, for reduced
action energy, and a smaller aperture maintaining and sustaining
pressure at a higher level for increased action energy.
[0006] Other purposes of the selectable aperture diameter include
the use of muzzle-mounted sound suppressors, which reduce the sound
of the report generated upon firing. These briefly capture the
pressurized gases emitted from the muzzle upon firing, so that the
impulse is absorbed and spread out. The resulting peak pressure
reduction provides a drastically reduced report. Suppressors also
have the effect of increasing "backpressure," because the
moderately high pressure gases temporarily stored serve to slow the
rate at which barrel bore pressures decline after the bullet exits
the muzzle. This means that there is more pressure, working for a
longer duration on the gas system. Consequently, the gas system
should generally be set to a smaller aperture when suppressors are
used, to avoid the problems with an over-pressurized gas
system.
[0007] While such gas system adjustments are satisfactory for use
with suppressors, problems can occur when a user installs a
suppressor, but forgets to set the gas plug to a smaller aperture.
This can cause unwanted damage, or a failure of the firearm to
properly perform (with potentially dire consequences in a combat or
self-defense context.)
[0008] The present invention overcomes the limitations of the prior
art by providing a gas-operated firearm having a barrel defining a
bore with a gas block defining a chamber communicating with the
bore via a gas passage. A gas regulation element has a first
position and a second position, and serves to provide different gas
flow characteristics in the different positions. The latch element
gives the user audible or tactile feedback upon installation of an
accessory device when the gas regulation element is a correct
position suited to use of the accessory, and not when in the other
position unsuited to accessory usage. The accessory may be a sound
suppressor, and the latch may serve to secure the gas regulation
element against position change. The latch may engage a circular
array of elements on the rear face of the suppressor, and may have
an angled cam face to provide ratcheting engagement for
installation, and to resist removal or loosening without deliberate
actuation of the latch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a side view of a rifle according to a preferred
embodiment of the invention.
[0010] FIG. 2 is a sectional view of the rifle of the preferred
embodiment.
[0011] FIG. 3 is an end view of the gas block of the preferred
embodiment.
[0012] FIG. 4 is an enlarged side view of the preferred embodiment
in a first operational condition.
[0013] FIG. 5 is an enlarged side view of the preferred embodiment
in a second operational condition.
[0014] FIG. 6 is an enlarged perspective view of a gas plug
according to a preferred embodiment of the invention.
[0015] FIGS. 7A and 7B are side and end views of the preferred
embodiment with a first gas plug setting.
[0016] FIGS. 8A and 8B are side and end views of the preferred
embodiment with a second gas plug setting.
[0017] FIG. 9 is a sound suppressor for use with the preferred
embodiment.
[0018] FIG. 10 is a sectional view of the suppressor attached to
the preferred embodiment.
[0019] FIG. 11 is a side view of the gas block of the preferred and
alternative embodiment.
[0020] FIG. 12 is a sectional view taken along line 12-12 of FIG.
11, of a gas plug according to an alternative embodiment.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0021] FIG. 1 shows a rifle 10 having a lower receiver 12, and an
upper receiver 14 in which a bolt assembly 16 reciprocates. A
barrel 20 extends forward from the upper receiver to a muzzle end
22. A gas block 24 is mounted to the barrel at an intermediate
position near the muzzle. An operating rod 26 has a cylindrical
piston 30 at a forward end, and has a rear end 32 that extends into
the upper receiver 14, and which is registered with a portion of
the bolt assembly 16. As will be discussed below, the piston 30 is
closely received within a cylindrical bore in the gas block, and a
passage extends between the cylinder and the barrel bore. Upon
firing, some of the pressurized column of gas behind the bullet
enters the gas block chamber and forces the piston rearward. The
rod then transmits energy to the bolt assembly, cycling it rearward
to load another round.
[0022] FIGS. 2 and 3 show the gas block 24 as mounted on the barrel
20. The barrel bore 34 extends axially through the barrel. The
barrel has an enlarged cylindrical profile portion 36 with a
narrower portion 40 extending forward. At the rear of the
cylindrical portion 36, a shoulder 42 is provided. The gas block 24
includes a cylindrical sleeve portion 44 defining a bore 45 that is
sized for a tight press fit or low-clearance slip fit on the barrel
portion 36, and has a comparable length. An upper block portion 46
extends above the sleeve portion and defines a generally
cylindrical bore 50 providing a passage through the block parallel
to the barrel bore.
[0023] The gas block passage 50 includes a forward portion 52 that
is a straight cylindrical bore with a circular cross-section.
Rearward of portion 52 is a fluted portion 54 having several axial
channels or flutes 56 that extend out the rear end 60 of the gas
block. The rearmost portion of the passage 50 is a shoulder portion
62 through which the flutes past, but with reduced diameter
sections providing shoulders 64 that face forward. A gas passage
aperture 66 is drilled laterally through the gas block toward the
forward end of portion 52, and aligns with a gas passage 70 drilled
in the barrel to provide communication between the barrel bore 34
and the gas block chamber.
[0024] The flutes 56 extend forward to a limit line 72 that defines
the limit between the forward portion 52 and rear portion 54 of the
gas block chamber. Each flute terminates at a flat surface 74
having an edge that follows the limit line 72. As shown in FIG. 3,
the flutes 56 extend radially to a significantly larger diameter
than the diameter of cylindrical section 52. In the preferred
embodiment, the cylinder portion 52 has a diameter of 0.452 inch,
and each flute extends radially beyond that by a distance of 0.042
inch. The reduced diameter at the shoulder portion 62 is 0.3126
inch. The flutes are generally semi cylindrical channels, so that
they do not have any sharp internal corners that would be
susceptible to fouling, and further to facilitate machining by
conventional processes. The rear portion 54 of the gas block
chamber includes cylindrical segments 76 that have the same
diameter as the forward portion 52 and are smoothly continuous
therewith. Thus, the cylindrical segment 76, and flutes 56
alternate in a rotationally symmetrical pattern as shown. In the
preferred embodiment, there are four flutes and four cylindrical
segments 76.
[0025] As shown in FIG. 4, a forward gas plug 80 encloses the
forward end of the gas block chamber. The plug has a cylindrical
sleeve 82 that extends into the forward end of the chamber, and
closely fits to seal against gas escape while permitting rotation.
The sleeve has a lateral aperture 84 that may be registered with
the gas hole 66 as shown to permit gas to be transmitted from the
barrel bore into the chamber. The sleeve has a rear end face 86
that is flat, and perpendicular to the axis of the gas block
chamber. The gas block may be provided with several different
diameter apertures, so that an aperture appropriate for the
circumstances may be selected. For instance, a larger aperture
provides greater gas flow and therefore a greater impulse to the
operating rod, while a smaller aperture reduces the force of the
operating rod. The gas plug may also have a position in which no
hole registers with the gas hole 66 so that the action does not
cycle with each shot.
[0026] The operating rod 26 has a straight rigid elongated shank 90
having a limited diameter that readily passes through the limited
aperture defined by the shoulder segment faces 62, with at least
some limited clearance as illustrated. The forward end of the rod
terminates with the enlarged piston 30, which has a flat circular
front face 92 and a flat annular rear shoulder 94. the lateral
cylindrical surface 96 of the piston is a smooth straight circular
cylinder that closely fits within a cylindrical section 52 of the
gas block chamber. A pair of circumferential annular grooves 100
encircles the piston at an intermediate position, spaced apart from
each other. These provide a reservoir where minor fouling can
accumulate without causing problems, and have edges that serve to
scrape the interior of the gas block chamber as the piston
cycles.
[0027] In FIG. 4, the piston is shown in a forward position to
which it is normally spring biased. The face 92 of the piston abuts
the rear face 86 of the plug, and the entire piston is surrounded
by the forward portion 52 of the chamber. In the illustrated
embodiment, the rear shoulder 94 of the piston aligns with the
plane 72 defined by the forward end faces 74 of flutes 56, although
this may vary as discussed below.
[0028] In FIG. 5, the piston 30 is in a rearmost position in which
the rear shoulder 94 abuts the shoulder 64 of the gas block.
Because the length of the piston (0.550 inch in the preferred
embodiment) is slightly greater than the distance between the
shoulder 64 and the flute end face 74 (0.540 inch in the preferred
embodiment) the face 92 of the piston never moves rearward far
enough to expose the flutes 56. Consequently, the gas piston
retains gas pressure in the chamber 52, so that it does not escape
rearwardly toward the shooter. Instead, the gas pressure dissipates
back through a gas hole through which it entered. An external vent
providing communication with the atmosphere may also be provided in
the gas block.
[0029] The flutes 56 provide that portions of the piston running
nearly its entire length are exposed when the piston is in the
rearward position. This permits any accumulated debris or fouling
to be readily shed each time the piston cycles. Because the piston
is free to rotate, different portions of the piston service are
exposed during operation, so that any localized fouling build up is
readily shed.
[0030] In alternative embodiments, the relationship between the
plane 72 and the forward face of the piston while in the rearward
position may be varied. Instead of the face being slightly forward
of the end of the flutes, the face may be aligned precisely with
the ends of the flutes, or may even be positioned slightly rearward
of the flute ends. This may be desirable in circumstances in which
gas needs to be vented rearward. This may be desired because
atmospheric vents on the gas block can create a visible jet that
can be seen in darkness. Exposed vents can also burn the user is
the jet is adjacent to exposed skin. In the illustrated embodiment,
the rearward venting path extends into a protected space within the
shrouded handguard that surrounds the barrel to the rear of the gas
block, preventing exposure and visibility of the vented gases.
[0031] FIG. 6 shows the gas plug 80. The gas plug's rear
cylindrical section 82 is connected at its forward end to a forward
portion 102 that has the form of an enlarged circular disk. The
rear section 82 includes a first lateral inlet aperture 84 and a
smaller lateral inlet aperture 104, both of which are positioned at
a similar distance from the rear face 86 of the plug. Consequently,
they may be registered with the barrel vent 70, depending on the
rotational orientation of the plug. This provides a choice of two
different effective aperture sizes, with the aperture being
selected based on the position of the plug. In general, the larger
aperture 84 is employed for normal rifle operations, and the
smaller aperture 104 is employed when a sound suppressor is
attached to the muzzle. This is because the aperture tends to
generate greater and more prolonged back pressure, which provides
more energy to the operating system than is desired.
[0032] The forward portion 102 of the gas plug has several features
defined in its periphery. A large arcuate scallop 106 is defined in
about one third of the periphery, and serves to provide clearance
for installation of the gas plug. A semicylindrical passage 110
extends through the entire thickness of the forward portion 102,
providing a small "bite" in the edge of the disk. A second
semicylindrical pocket 112 is defined at another position on the
disc's periphery, separated from the first passage 110 by the same
rotational angle by which aperture 84 is separated from aperture
104. Pocket 112 differs from passage 110 in that it does not extend
the full thickness of the disk. The pocket 112 extends only about
two thirds of the thickness of the disk, so that it does not
penetrate the front surface 114 of the disk. The pocket thus
defines a rearward facing surface 116 that represents the forward
limit of the pocket.
[0033] In the preferred embodiment, the passage 110 and pocket 112
are angularly separated. The passage 110 and pocket 112 have a
common radius, with their axes extending parallel to the axis of
the plug.
[0034] FIGS. 7A and 7B show a captive latch pin element 120 that is
essentially an elongated rod oriented parallel to the firearm axis
that reciprocates along the axis. The latch is biased in a forward
direction to a forward position as shown. The forward end of the
latch includes an angled cam surface 122, and the rest of the latch
is received within a bore 124 defined within the gas block. A coil
spring 126 within the bore provides biasing, by generating pressure
between a shoulder 130 on the latch pin and a shoulder 132 within
the bore 124. A C-ring 134 is received by a circumferential groove
near the rear end 136 of the latch pin, and is installed on the pin
after the pin is installed in the bore to limit forward excursion
of the latch. The body of the pin is a smooth cylinder with a
diameter sized to closely fit within the channel 110. A vent
aperture 138 axially drilled in the front of the gas plug provides
a gas passage between the bore of the gas plug and atmosphere, so
that gas pressure in the plug is dissipated after firing each
shot.
[0035] The setting of the gas plug is changed by sliding a button
140 that extends laterally from the pin in a rearward direction
until the forward end of the latch is to the rear of the forward
section 102 of the gas plug. This allows the plug to be rotated,
such as to align the pocket 112 with the latch. As shown in FIGS.
8A and 8B, the gas plug 80 has been rotated into a second position,
in which the latch extends into the pocket 112, securing the plug
against rotation. A forward portion of the latch rests against the
surface 116, preventing the forward end of the latch from extending
beyond the forward face 114 of the gas plug.
[0036] Thus, while the gas plug is secured against rotation in
either of the positions shown, the protruding latch shown in FIG.
7A indicates that the smaller hole 104 is providing limited gas
flow from the barrel, while the partially retracted latch shown in
FIG. 7B indicates that the larger hole 84 is providing gas
flow.
[0037] This feature of latch position depending on plug position is
used beneficially when a muzzle mounted sound suppressor 142 is
secured to the threads 144 at the forward end of the gas block
element. As shown in FIG. 9, the suppressor 142 has a rear end 146
defining a threaded bore 150 with threads that engage the threads
144 on the gas block. The rear face of the suppressor includes a
annular ring 152 having a pattern of notches or teeth 154. As shown
in FIG. 10, each tooth 154 has an angled forward face 156 that is
angled to match the cam surface 122 of the latch 120. Each tooth
has a flat back face 160 that is perpendicular to the plane of the
rear face 146, and aligned radially with respect to the axis of the
suppressor.
[0038] The interaction of the suppressor teeth 154 and the latch
120 (when in the extended position shown in FIG. 10 and in FIG. 7A)
provides multiple benefits. First, it prevents unwanted loosening
of an attached suppressor. A flat rear face 162 of the latch
engages its corresponding face 160 of the suppressor, keeping the
suppressor securely attached until the latch is deliberately
retracted to allow it to be unscrewed. This provides important
safety benefits by avoiding the dangerous condition of firing with
a loose and misaligned suppressor.
[0039] When the suppressor is installed by screwing in onto the
threads 144, as it moves rearward interposition, the suppressor
teeth 154 begin to encounter the latch 120. Normally, the latch is
not retracted during this process and the cam surface 122 engages
the angled surfaces 156 of the suppressor. Because of the matching
angles, the cam is pushed rearward by the teeth as each tooth
passes, and operates like a ratchet. This provides clear tactile
and audible feedback to the user, reminding him that the gas plug
is in the desired position intended for suppressor usage. Should
the user have forgotten to set the gas plug in the proper position,
he will receive no feedback from the ratchet mechanism. This will
be a clear indication that the plug setting is in error, allowing
the setting to be corrected in avoiding the associated risk and
damage.
[0040] When a suppressor is not used, but the plug is in the
setting for suppressor use, the protruding latch provides visual
indication of an improper gas plug setting.
Alternative Embodiment
[0041] FIG. 11 shows the gas block 24 on the left side,
illustrating a vent hole 170 that exists in either embodiment. As
discussed above, gas pressure in the gas block chamber is
dissipated through the vent hole, at a relative slow rate following
exit of the bullet from the muzzle. In the embodiment above, the
cylindrical portion 82 of plug 80 includes two vent apertures, each
registering with the vent hole 170 for one of the gas plug
positions discussed above. In the above embodiment, the cylinder
vent holes are equal in size. They may be larger than the vent hole
170, which is sized to limit flow, or they may be smaller, to
provide the vent flow limitation orifice.
[0042] An alternative plug 180 is shown in FIG. 12, with a
cylindrical portion 182 defining at a forward position a small vent
aperture 184 and a large vent aperture, each of which registers
with gas block vent hole 170 when in one of the two plug positions.
In this embodiment, a corresponding pair of inlet apertures 186,
190 are defined in the plug's cylindrical portion at a position
rearward of the vent apertures. The inlet apertures are of the same
large size, each registering with the gas block aperture 66 when in
the two respective operational positions. These provide gas
transmission from the barrel to operate the action. All functions
of interaction with the suppressor are the same as in the above
embodiment, and this alternative is shown to indicate that either
the gas block inlet or outlet (vent) adjustment may be used to
provide functionality with or without a suppressor, and with the
latch used to indicate whether the plug is in a suitable position
for suppressor operation.
[0043] While the above is discussed in terms of preferred and
alternative embodiments, the invention is not intended to be so
limited.
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