U.S. patent application number 10/693784 was filed with the patent office on 2005-06-02 for gas-operated guns with demountable and interchangeable barrel sections and improved actuation cylinder construction.
Invention is credited to Olson, Douglas D..
Application Number | 20050115398 10/693784 |
Document ID | / |
Family ID | 34619772 |
Filed Date | 2005-06-02 |
United States Patent
Application |
20050115398 |
Kind Code |
A1 |
Olson, Douglas D. |
June 2, 2005 |
Gas-operated guns with demountable and interchangeable barrel
sections and improved actuation cylinder construction
Abstract
Gas-operated automatic and semi-automatic guns are improved by
having a bisectional barrel with demountable and interchangeable
muzzle sections wherein the breech section has a rifled bore and by
having an actuation cylinder mounted to the receiver instead of the
barrel. The muzzle sections are connected to the breech section via
a tapered plug that locks into a tapered socket of the breech
section. A port in the tapered plug joins with a port in the
tapered socket to deliver gas from the barrel bore to the actuation
cylinder and the tapered plug port in each interchangeable muzzle
section is sized to provide automatic control of the proper amount
of gas to cause the gun to function at its best rate based on the
ammunition, silencer and length of the particular muzzle section
selected by the user.
Inventors: |
Olson, Douglas D.; (Vero
Beach, FL) |
Correspondence
Address: |
LAW OFFICES OF BRIAN S STEINBERGER
101 BREVARD AVENUE
COCOA
FL
32922
US
|
Family ID: |
34619772 |
Appl. No.: |
10/693784 |
Filed: |
October 27, 2003 |
Current U.S.
Class: |
89/193 |
Current CPC
Class: |
F41A 5/18 20130101; F41A
5/26 20130101; F41A 21/00 20130101 |
Class at
Publication: |
089/193 |
International
Class: |
F41A 005/00 |
Claims
1. A gas-operated gun comprising: a bisectional barrel having a
breech section defined by a breech front portion and a breech rear
portion and a plurality of demountable and interchangeable muzzle
sections, each muzzle section being defined by a muzzle front
portion and a muzzle rear portion, a chamber defined by a rear end
and a front end, said chamber being operatively connected by said
front end to said breech rear portion, a receiver to which said
chamber is mounted to accept ammunition therein, and an actuation
cylinder mounted to said receiver for operation by gas delivered
via tubular means from said bisectional barrel to said actuation
cylinder, a mechanical system operated by said actuation cylinder
to perform gun functions of unlocking, extraction, ejection,
feeding and relocking, said breech section comprising a rifled bore
that extends forward of said front end of said chamber, the front
end of said breech front portion being defined by an tapered socket
having a base and each rear end of each said muzzle rear portions
being defined by a tapered plug having face, said tapered plugs
being configured to mate with said tapered socket, and the
bisectional barrel formed by said muzzle section being joined to
said beech section by junction of said tapered plug with said
tapered socket.
2. The gas-operated gun of claim 1 further comprising: an alignment
pin extends forward from said tapered socket to operatively align
said muzzle section with said beech section.
3. The gas-operated gun of claim 2 wherein: the front end of said
breech section has external threads that mate with threads of a
collar nut captive on the rear end of the muzzle section to
operatively connect the muzzle section to the breech section to
provide a continuous bore from the rear end of said breech section
to said front end of said muzzle section.
4. The gas-operated gun of claim 3 wherein: said tapered plugs of
said muzzle sections have a first port that joins with a second
port in said base of said tapered socket of said breech section and
the combination of said first and second ports provide a passage
for propellant gas to flow from said bore of said gun barrel to
said actuation cylinder.
5. The gas-operated gun of claim 4 wherein: said first ports are
sized to control the volume of gas that is passed to said actuation
cylinder.
6. The gas-operated gun of claim 4 wherein: said front end of said
muzzle sections are externally threaded to attach auxiliary
devices.
7. The gas-operated gun of claim 4 wherein: there is approximately
six inches of rifled bore to cause a projectile fired from said gun
to spin at a rotational velocity that is sufficient to stabilize
the flight of the projectile.
8. The gas-operated gun of claim 1 wherein: said muzzle sections
comprise smooth bores.
9. A gas-operated gun comprising: a barrel defined by a breech end
and a muzzle end and containing a bore, a chamber defined by a rear
end and a front end by which said chamber is operatively connected
to said breech end of said barrel, a receiver to which said rear
end of said chamber is mounted to accept ammunition therein, an
actuation cylinder mounted to said receiver with a portion of said
receiver extending over said actuation cylinder and over said
breech portion of said barrel, a mechanical system positioned in
said receiver and operated by said actuation cylinder to perform
the gun functions of unlocking, extraction, ejection, feeding and
relocking, and a tube connecting said bore of said barrel to said
actuation cylinder for passage of propellant gas from said bore to
said actuation cylinder while effectively shielding said barrel
from positional movements of said actuation cylinder caused by
interaction between said actuation cylinder and said mechanical
system.
10. The gas-operated gun of claim 9 wherein: threaded fasteners
serve to support said actuation cylinder in said receiver and
enable the free floating of said barrel.
11. A gas-operated gun comprising: a bisectional barrel having a
breech section defined by a breech front portion and a breech rear
portion and a plurality of demountable and interchangeable muzzle
sections, each muzzle section being defined by a muzzle front
portion and a muzzle rear portion, said breech section comprising a
rifled bore that extends forward from said front end of said
chamber and said muzzle sections comprise smooth or rifled bores,
the front end of said breech front portion being defined by an
tapered socket having a base and each rear end of each said muzzle
rear portions being defined by a tapered plug having a rear face,
said tapered plugs being configured to mate with said tapered
socket, the bisectional barrel being formed by said muzzle section
being joined to said beech section by junction of said tapered plug
with said tapered socket, a chamber defined by a rear end and a
front end by which said chamber is operatively connected to said
breech rear portion, a receiver to which said rear end of said
chamber is mounted to accept ammunition therein, and an actuation
cylinder mounted to said receiver with a portion of said receiver
extending over said actuation cylinder and over said breech end of
said barrel, a mechanical system positioned in said receiver and
operated by said actuation cylinder to perform the gun functions of
unlocking, extraction, ejection, feeding and relocking, and a
shaped tube connecting said bore of said barrel to said actuation
cylinder for passage of propellant gas from said bore to said
actuation cylinder while effectively shielding said barrel from
positional movements of said actuation cylinder caused by
interaction between said actuation cylinder and said mechanical
system.
12. In a gas-operated gun comprising: a receiver, an actuation
cylinder, a mechanical system positioned in said receiver and
operated by said actuation cylinder to perform the gun functions of
unlocking, extraction, ejection, feeding and relocking, a chamber a
chamber defined by a front end and a rear end by which said chamber
is operatively connected to said receiver, a barrel having a bore
and tube means to conduct gas from said bore to said actuation
cylinder, the improvement that comprises; said barrel being a
bisectional barrel having a breech section defined by a breech
front portion and a breech rear portion and a plurality of
demountable and interchangeable muzzle sections, each muzzle
section being defined by a muzzle front portion and a muzzle rear
portion, the front end of said breech front portion being defined
by an tapered socket having a base and each rear end of each said
muzzle rear portions being defined by a tapered plug having face,
said tapered plugs being configured to mate with said tapered
socket, and the bisectional barrel being formed by said muzzle
section being joined to said beech section by junction of said
tapered plug with said tapered socket.
13. The gas-operated gun of claim 12 wherein: said tapered plugs of
said muzzle sections have a first port that joins with a second
port in said base of said tapered socket of said breech section,
the combination of said first and second ports providing a passage
for propellant gas to flow from said bore of said gun barrel to
said actuation cylinder and said first ports are sized to control
the volume of gas that is passed to said actuation cylinder.
14. In a gas-operated gun comprising: a receiver, an actuation
cylinder, a mechanical system positioned in said receiver and
operated by said actuation cylinder to perform the gun functions of
unlocking, extraction, ejection, feeding and relocking, a barrel
defined by a breech end and a muzzle end and containing a bore, and
tube means to conduct gas from said bore to said actuation
cylinder, the improvement that comprises having said actuation
cylinder mounted to said receiver for its support in said gun.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates broadly to gas-operated automatic and
semi-automatic guns, especially rifles. More particularly, it
concerns such guns that comprise (a) a bisectional barrel with
demountable and interchangeable muzzle sections and (b) an
actuation cylinder mounted to the receiver instead of the
barrel.
[0003] 2. Description of the Prior Art
[0004] There is a recognized need for guns that can easily change
barrel length and that can facilitate the use of non-standard
ammunitions in battle conditions. This invention provides
improvements in gun construction that supply these needs with
greater weapon reliability and adaptability than has been
attainable with prior known guns.
[0005] It is known to construct guns with bisectional barrels in
which the breech section bore is smooth and the muzzle section bore
is rifled. Thus, U.S. Pat. Nos. 4,546,564 and 4,660,312 disclose
such bisectional barrels in which the rear end of the muzzle
section threads into the front end of the breech section while USS
Reg. No. H1365 discloses bisectional gun barrels in which a rifled
bore muzzle section is fixed at its rear end to the front end of
the breech section by a collar.
[0006] Rifles with barrels having a rifled bore breech section and
a smooth bore muzzle section have also been previously disclosed in
U.S. Pat. No. 4,527,348.
[0007] Gas operated guns capable of firing several different
cartridges and that permit a user to adjust the gas systems to
change the amount of gas used to cycle the gun's operating system
to compensate for differences in cartridges have been disclosed in
U.S. Pat. No. 5,900,577.
[0008] There is also a recognized need for gas-operated guns that
can provide a consistently low dispersion of fired shots without
being detrimental to reliable functioning of the gun. This
invention provides improvements in gun construction that meet this
need.
[0009] There are a large number of weapons that have been developed
and sold having a gas cylinder that is mounted directly to the
barrel. Notable examples are the Soviet AK family, FN FAL, and the
US M1, M14, M1 Carbine and M60 Machine Gun. In these weapons the
propellant gas is ported from the barrel into the gas system which
then creates a rearward force that pushes the operating mechanism
of the weapon to the rear to perform the functions of unlocking,
extraction, ejection, feeding and relocking the bolt, e.g., see
U.S. Pat. Nos. 4,475,438 and 5,246,758.
[0010] With all of these systems the barrel becomes the structural
member that directly resists the energy supplied to create the
rearward travel of the operating mechanism components. This load on
the barrel results in unwanted barrel movement at the time the
projectile leaves the muzzle causing serious dispersion of the
resulting shots. The M16 Rifle made a notable change from this
historical pattern in that it transmitted the gas to a gas cylinder
within the receiver via a gas tube, e.g., see U.S. Pat. Nos.
4,765,224; 5,351,598 and 5,726,377. The AR10/AR15 family of weapons
thus enjoyed a substantially better accuracy than all of its
predecessors.
[0011] The gas tube transports the propellant gas from the barrel
to the bolt carrier where that pressure is subjected to the rear of
the bolt and the bolt carrier. When the pressure is applied, the
bolt cannot move forward because it is pushing against the
cartridge case and the rear of the barrel. The loads applied to the
barrel at that location are offset by the loads applied by the same
chamber pressure pushing back against the bolt. Even though there
are big loads involved at the bolt to barrel junction, those loads
are all in-line with the axis of the barrel and cause no barrel
deflection. What can move is the bolt carrier, which, as a result
of the pressure, starts to move to the rear. When the bolt carrier
has moved approximately 0.30 inches, ports open and exhaust the gas
pressure to atmosphere. The load that is transmitted to the barrel
is the product of the instantaneous pressure inside the gas tube
and the cross-sectional area of the gas tube. Similarly, the load
applied between the bolt and the bolt carrier is the product of the
piston area times the same instantaneous pressure. In the case of
the M16 family of rifles the cross-sectional area of the bolt
piston is 0.138 square-inches vs. the 0.025 square-inches of the
gas tube. Thus the M16 applies only 18% of the load required to
operate the gun to the barrel instead of the 100% that most guns
apply. Hence it is easy to see that the deflection of the barrel is
far less when a gas tube is used. The AR10/AR15 family of weapons
thus enjoyed a substantially better accuracy than all of its
predecessors.
[0012] The drawback to the M16 design is that it dumps that gas
directly into the working mechanism that has historically been a
detriment to reliable functioning. The present invention provides
new gun constructions that eliminate such detriment.
OBJECTS
[0013] A principal object of the invention is the provision of
improvements in construction of gas-operated automatic and
semi-automatic guns, especially rifles, by the provision of new
types of guns that comprise bisectional barrels with demountable
and interchangeable muzzle sections.
[0014] Another object is the provision of gas-operated automatic
and semi-automatic guns comprising actuation cylinders mounted to
the receiver instead of the barrel.
[0015] Further objects include:
[0016] 1. The provision of gas-operated automatic and
semi-automatic guns with bisectional barrels capable of
automatically altering firing parameters with changes in muzzle
barrels to accommodate for multiple versions of non-standard
ammunitions.
[0017] 2. The provision of gas-operated guns that can provide a
consistently low dispersion of fired shots without being
detrimental to reliable functioning of the gun.
[0018] 3. The provision of gas-operated guns that do not dump
operation gas directly into the breech working mechanism.
[0019] 4. The provision of improvements in guns that have
particular application to the M16/M4 series of rifles.
[0020] Other objects and further scope of applicability of the
present invention will become apparent from the detailed
descriptions given herein. It should be understood, however, that
the detailed descriptions, while indicating preferred embodiments
of the invention, are given by way of illustration only, since
various changes and modifications within the spirit and scope of
the invention will become apparent from such descriptions.
SUMMARY OF THE INVENTION
[0021] The objects are accomplished in part by the invention via
provision of improved guns that comprise a bisectional barrel
configured with a breech section and a muzzle section, selected
from a plurality of muzzle sections, operatively joined by a unique
socket type connection. In preferred embodiments, the bore of the
breech barrel section is rifled and the bore of the muzzle section
is either smooth (without any rifling) or is rifled as suits the
specific application. Further, the rear of the breech section is
fitted to a chamber that operatively connects the breech section to
the gun's receiver. The length of the breech section remains
constant while the total length of the gun varies with the length
of the muzzle section selected from time to time by the user.
[0022] In preferred embodiments, the front end of the constant
length breech section is approximately eight inches forward of the
back of the chamber. There is approximately six inches of
conventionally rifled bore. This breech section length is long
enough to cause projectiles shot from the gun to spin at a
rotational velocity that is sufficient to stabilize the flight of
the projectile.
[0023] The forward end of the breech section terminates with a
tapered socket that mates with a tapered plug at the rear end of a
muzzle section to form the full bisectional barrel.
[0024] An alignment pin extends rearwardly from the tapered plug to
operatively align the muzzle section with the beech section.
[0025] The front end of the breech section has external threads
that mate with threads of a collar nut captive on the rear end of
the muzzle section to operatively connect the muzzle section to the
breech section to provide a continuous bore from the rear end of
the breech section to the front end of the muzzle section.
[0026] The front end of the muzzle section is externally threaded
to attach various auxiliary devices, e.g., silencers and
multifunctional muzzle attachments as disclosed in U.S. Pat. No.
6,595,099, the contents of which are incorporated herein by
reference.
[0027] The rear face of the tapered plug of the muzzle section has
a first radial port that joins with a second radial port in the
base of the tapered socket of the breech section. The combination
of the first and second radial ports provides a passage for
propellant gas to flow from the bore of the gun barrel to the
outlet end of the second radial port to provide the gas pressure
for the operation of the gun.
[0028] The size of the first radial port controls the volume of gas
that is released to the gas system of the gun. Hence, each muzzle
barrel portion can be selectively tuned by sizing its first radial
port to provide the proper amount of gas to automatically cause the
weapon to function at its desired cyclic rate based on the
ammunition, silencer and length of the muzzle section selected by
the user.
[0029] As a further improvement of the invention, there can be
provided a silencer that interfaces directly with the breech
section of the barrel with the same attachment mechanism that has
the proper gas port size for use with that silencer-ammunition
combination.
[0030] A further improvement in gun construction provided by the
invention is to mount the actuation cylinder directly to the
receiver. A mechanical system operated by the actuation cylinder
performs the gun functions of unlocking, extraction, ejection,
feeding and relocking,
[0031] The operation gas is transmitted from the barrel to the
actuation cylinder thru a flexible tube that effectively isolates
the barrel from the mechanical system. In this way the invention
provides a system that keeps the propellant gas out of the other
working portions of the gun. The invention achieves this by
attaching the barrel to the receiver in an un-conventional manner
so the invention provides a gun that has the reliability and
cleanliness of a gas piston forward of the bolt and bolt carrier
with the accuracy associated with a free-floating barrel.
[0032] The actuation cylinder housing is mounted to the upper
receiver with threaded fasteners (flat head machine screws) and
with two dowel pins. The actuation cylinder housing fits into a
longitudinal slot in the upper receiver that supports the sides of
the actuation cylinder housing. Axial loads (along the axis of the
barrel) are taken by the dowel pins. The actuation cylinder has
appendages protruding from its top surface that act as the anchor
points to the upper receiver.
[0033] The gas tube transports the propellant gas from the barrel
to the actuation cylinder. The gas pressure acts via the actuation
cylinder upon the mechanical system to perform the gun functions of
unlocking, extraction, ejection, feeding and relocking, by the
force of the applied gas to the actuation cylinder. The reaction
forces from all of this motion are transferred directly to the
receiver via the anchor points on the actuation cylinder. In this
way the barrel sees only what strain can be applied to it by the
pressure buildup in the gas tube. In this case the effective load
applied to the barrel is even less than the 18% that the M16/M4
sees because the gas tube is rigidly attached at each end
preventing it from acting as a piston.
[0034] The barrel is mounted to the upper receiver with a
combination of a bonded joint, four bolts and additionally
supported by the guide rails for the bolt. In preferred
embodiments, the barrel is bonded to the carbon-fiber upper
receiver with an epoxy-based compound. When the bond joint is laid
in, four machine screws pull the barrel into contact with the upper
receiver keeping the bond joint as thin as possible. After the
barrel joint has cured, the guide rails for the bolt and bolt
carrier are bonded and riveted in place behind the barrel. The
barrel mounting thus described provides a method of achieving a
full floating barrel where foreword, beyond the chamber, the barrel
does not contact the handguard or the gas system except with the
gas tube. Accordingly, guns made in accordance with the invention
have greater accuracy than guns whose gas system mounts to the
barrel and the reaction forces from that interaction are
mechanically taken by the barrel.
[0035] In accordance with a preferred embodiment of the invention,
the gas is transmitted from the gun barrel to the actuation
cylinder thru a "U" shaped tube that effectively isolates the
barrel from the actuation cylinder. In this way, the invention
provides a new system that keeps the propellant gas out of the
other working portions of the weapon. This is attained in
accordance with the invention with threaded fasteners and the guide
rails for the mechanical system that is fastened to the receiver as
well. The result is a weapon that has the reliability and
cleanliness of a gas piston forward of the bolt and bolt carrier
with the accuracy associated with a free-floating barrel.
[0036] Construction of guns in accordance with the invention will
prove to be beneficial to gun users who want the ability to change
the length of the barrel as well as those who want to tune the gun
to work optimally with a particular round of ammunition or
silencer. In the past what was required was having a dedicated
upper receiver assembly for each of these instances. The volume
required to store these front barrel extensions is dramatically
less that than required for the storage of the complete upper
receiver assembly. The front barrel extensions are also much less
expensive than an entire new upper receiver assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] A more complete understanding of the invention can be
obtained by reference to the accompanying drawings in which:
[0038] FIG. 1 is an elevational side view of the forward part of
one preferred embodiment of a rifle constructed in accordance with
the invention equipped with the medium length version of the barrel
muzzle section, selected from the gun's plurality of muzzle
sections.
[0039] FIG. 2 is a longitudinal sectional side view corresponding
to FIG. 1.
[0040] FIG. 3 is an enlarged isometric rear view of the long
version of a muzzle section of the gun shown in FIG. 1.
[0041] FIG. 4 is an enlarged isometric rear view of the medium
length version of a muzzle section of the gun shown in FIG. 1.
[0042] FIG. 5 is an enlarged isometric rear view of the short
version of a muzzle section of the gun shown in FIG. 1.
[0043] FIG. 6 is an enlarged sectional view of a central portion of
the rifle as shown in FIG. 1.
[0044] FIG. 7 is a right side view of the forward end of the rifle
of FIG. 1 with the receiver removed.
[0045] FIG. 8 is an isometric front-end view of the breech muzzle
section of the rifle of FIG. 1.
[0046] FIG. 9 is a left side view of the rifle similar to the right
side view of FIG. 7.
[0047] FIG. 10 is an enlarged oblique view of the middle portion of
the left side of the rifle of FIG. 1 with the receiver in
place.
[0048] FIG. 11 is an enlarged oblique view of the middle portion of
the right side of the rifle similar to FIG. 10, but more clearly
showing that the actuation cylinder does not touch the barrel of
the rifle.
[0049] FIG. 12 is a sectional view taken along line 12-12 of FIG.
10.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0050] Referring in detail to the drawings beginning with FIGS. 1
& 2, the improved gun 2 of the invention comprises a
bisectional barrel 4 having a breech section 6 defined by a breech
front portion 8 and a breech rear portion 10 plus a demountable and
interchangeable muzzle section 12 defined by a muzzle front portion
14 and a muzzle rear portion 16.
[0051] The gun 2 includes chamber 18 that is defined by a rear end
20 and front end 22. Chamber 18 is operatively connected by its
front end 22 to breech rear portion 10.
[0052] The receiver 24 constitutes a major component of the gun 2.
The rear end 20 of chamber 18 is mounted to receiver 24 to accept
ammunition therein in known fashion of operation of M16 rifles.
Also, an actuation cylinder 26 is mounted to the receiver 24 in
manner explained further below.
[0053] Located within the receiver 24 there is a mechanical system
28, operated by the actuation cylinder 26, to perform in known
manner the gun functions of unlocking, extraction, ejection,
feeding and relocking.
[0054] The rear portion 10 of breech section 6 bears external
threads 29 to connect the breech section 6 to the front end 22 of
chamber 18.
[0055] The breech section 6 comprises a rifled bore 30 that extends
forward from the front end 22 of the chamber 18 and the muzzle
section 12 comprises a smooth bore 32.
[0056] Referring to drawings 3-5, in a preferred embodiment of the
invention there is a complement of three interchangeable muzzle
sections of different length. Thus, long muzzle section 12 is shown
in FIG. 3, medium muzzle section 12M is shown in FIG. 4 and the
short muzzle section 12S is shown in FIG. 5, enlarged relative to
FIGS. 3 & 4 to more clearly show structural details.
[0057] Referring now to FIG. 6, the front end 32 of front portion 8
of the breech portion 6 of gun 2 is defined by an tapered socket 34
having a base 36. The rear end 38 of muzzle rear portion 16 is
defined by a tapered plug 40 having face 42. The tapered plug 40 is
configured to mate with the tapered socket 34 and the bisectional
barrel 4 is formed by joining muzzle section 12 to beech section 6
by junction of the tapered plug 40 with the tapered socket 34. To
do this, the front end 8 of breech section 6 has external threads
44 that mate with threads 46 of a collar nut 48 captive on the rear
end of the muzzle section 12 to operatively connect the muzzle
section 12 to provide a continuous bore B from the rear end of said
breech section (not shown in FIG. 6) to said front end of muzzle
section 12 (not shown in FIG. 6).
[0058] Referring to FIGS. 5, 6 & 8, the tapered plug 40 of
muzzle section 12S has a first port 50 that joins with a second
port 52 in the base of tapered socket 34 of the breech section 6.
The combination of first and second ports 50 & 52 provides a
passage for propellant gas to flow from the bore B of the gun
barrel to said actuation cylinder 26. The first port 50 is sized to
control the volume of gas that is passed to actuation cylinder 26
and this sizing feature applies to other muzzle sections, e.g.,
middle length muzzle section 12M (FIG. 4) and long length muzzle
section 12 (FIG. 3).
[0059] An alignment pin 53 extends forward from the tapered socket
34 to operatively align the muzzle section 12 with the beech
section 6. Tapered plug 40 contains a groove 54 to receive one end
of the alignment pin 53 and breech section 6 also contains a groove
54A to receive the other end of alignment pin 53.
[0060] The front ends of the muzzle sections 12, 12M & 12S have
external threads 55 to attach auxiliary devices A (see FIG. 1).
[0061] Referring to FIGS. 6-11, the actuation cylinder 26 is
mounted to the receiver 24 (not shown in FIGS. 7 & 9) that
extends over a portion of the actuation cylinder 26 and over most
of the breech portion 6 of the barrel 4.
[0062] As previously noted, the mechanical system 28 is positioned
in the receiver 24 and operated by the piston 59 of the actuation
cylinder 26 to perform the gun functions of unlocking, extraction,
ejection, feeding and relocking.
[0063] A "U" shaped tube 60 connects the bore B of the barrel 4 to
the actuation cylinder 26 for passage of propellant gas from the
bore B to the actuation cylinder 26 while effectively shielding the
barrel 4 from positional movements of the actuation cylinder 26
caused by interaction between the actuation cylinder 26 and the
mechanical system 28.
[0064] Threaded fasteners 62 help support the actuation cylinder 26
and the mechanical system 28 in the receiver 24 and enable the free
floating of the barrel 4. Dowel pins 63 take loads along the axis
of the barrel 4.
[0065] With reference to FIGS. 6-9, a complex collar 64 surrounds
the front end 32 of front portion 8 of the breech portion 6 of gun
2. The collar 64 comprises a hood 66 that is positioned over the
second port 52 to receive gas from the barrel bore B via the
passage formed of first port 50 and second port 52. In turn, the
inlet end 68 of U-tube 60 is connected to the hood 66 to conduct
the ported gas to the outlet end 70 of U-tube 60 for discharge into
the actuation cylinder 26 to reciprocate the piston 59 for
operation of the mechanical system 28.
[0066] Tests using M16 rifles with bisectional barrels in
accordance with the invention have recorded a slight increase in
projectile velocity over that of the one-piece barrel of the same
length. Also, the tests have revealed improved accuracy and point
of impact shift as the barrels are changed. The taper socket/plug
connection of breech barrel section 6 with muzzle barrel section 12
has demonstrated the ability to consistently repeat. It was found
that a 16-degree included angle for the sockets 34 and plugs 40 is
as small as one should go without having the taper become
self-locking. The gap between the rear 42 of the front barrel
section 12 and the base 36 of the socket 34 in the breech barrel
section 6 is controlled through the use of gauging and grinding the
seats and taper portions of the sockets 34 and plugs 40.
* * * * *