U.S. patent application number 12/297642 was filed with the patent office on 2009-04-23 for bolt head locking arrangement for firearm weapons.
Invention is credited to Douglas Rawson-Harris.
Application Number | 20090101000 12/297642 |
Document ID | / |
Family ID | 38608970 |
Filed Date | 2009-04-23 |
United States Patent
Application |
20090101000 |
Kind Code |
A1 |
Rawson-Harris; Douglas |
April 23, 2009 |
BOLT HEAD LOCKING ARRANGEMENT FOR FIREARM WEAPONS
Abstract
A bolt head locking arrangement for a recoil operated weapon
where projectile is expelled by discharging a cartridge. The weapon
comprising an action body, a barrel, and a bolt assembly, the bolt
assembly being slidable within the action body. The bolt assembly
comprising a bolt head, a locking slide and a firing pin, and a
locking means arranged so that, upon loading a new cartridge for
discharging, the locking means positively lock the bolt head such
that, for a predetermined amount of time after the loaded cartridge
is discharged, the locked bolt head stops the cartridge from
retreating into the action body. The locking means is substantially
in an in-line configuration with the bolt assembly. The locking
means are arranged so that the recoil momentum of the weapon,
caused by the discharge, is used for unlocking the bolt head,
wherein the locking means are arranged so that, upon discharge of
the cartridge, the locking slide recoils backwards and, once the
bolt head is unlocked, the inertia of the locking slide facilitates
the recoil of the bolt head.
Inventors: |
Rawson-Harris; Douglas; (New
South Wales, AU) |
Correspondence
Address: |
DANIEL B. SCHEIN, PH.D., ESQ., INC.
P. O. BOX 68128
Virginia Beach
VA
23471
US
|
Family ID: |
38608970 |
Appl. No.: |
12/297642 |
Filed: |
April 17, 2007 |
PCT Filed: |
April 17, 2007 |
PCT NO: |
PCT/AU2007/000493 |
371 Date: |
November 27, 2008 |
Current U.S.
Class: |
89/183 ;
42/70.08; 89/190 |
Current CPC
Class: |
F41A 3/40 20130101; F41A
3/62 20130101 |
Class at
Publication: |
89/183 ; 89/190;
42/70.08 |
International
Class: |
F41A 3/62 20060101
F41A003/62; F41A 3/36 20060101 F41A003/36; F41A 3/38 20060101
F41A003/38 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 19, 2006 |
AU |
2006902030 |
Claims
1. A bolt head locking arrangement for a recoil operated weapon
where projectile is expelled by discharging a cartridge, the weapon
comprising a longitudinal action body, a longitudinal barrel, the
barrel being a part of or axially attached to the action body, and
a bolt assembly, the bolt assembly being slidable within the action
body so as to affect at least one of; loading cartridges in the
barrel for discharging, discharging cartridges and extracting
discharged cartridges; the bolt assembly comprising a bolt head, a
locking slide and a firing pin, at least some of which being
arranged for moving with respect to each other, wherein the
arrangement further comprises locking means arranged so that, upon
loading a new cartridge for discharging, the locking means
positively lock the bolt head such that for a predetermined amount
of time after the loaded cartridge is discharged, the locked bolt
head stops the cartridge from retreating into the action body, thus
eliminating the penetration of pressure caused by the discharge
into the action body, the locking means is substantially in an
in-line configuration with the bolt assembly, and said locking
means are arranged so that the recoil momentum of the weapon,
caused by the discharge, is used for unlocking the bolt head, and
the locking means are arranged so that, upon discharge of the
cartridge, the locking slide recoils backwards and, once the bolt
head is unlocked, the inertia of the locking slide facilitates the
recoil of the bolt head, wherein the locking slide comprises a
timing surface of predetermined length and the locking means
comprise at least one locking lug that is engageable with the
timing surface so as to move between open and closed configuration,
wherein in the closed configuration the at least one lug is located
within the cross-sectional area of the bolt head to allow the
sliding movement of the head within the action body, while in open
configuration the at least one lug extends beyond this
cross-sectional area to abut with an abutment surface of the action
body and prevent rearward movement of the bolt head, wherein in
use; when the bolt assembly is moved forward to load a cartridge,
the locking slide moves with respect to the bolt head so that the
timing surface engages the at least one lug to push it into an open
configuration, so that when the bolt head is moved fully forwardly,
the bolt head is locked in a sealing engagement with the sealing
inner surface of the barrel and in an abutment engagement with the
abutment surface of the action body; and upon discharging the
cartridge, the locking slide moves backwards, causing the entire
predetermined length of the timing surface to withdraw from its
engagement with the at least one lug and allow the at least one lug
to move into closed configuration, thus unlocking the bolt head and
allowing it to recoil.
2. The arrangement of claim 1, wherein the locking means are
arranged so that, after the bolt head is unlocked, a residual of
the gas pressure formed during the discharge is used for assisting
with the recoil of the bolt head.
3. The arrangement of claim 1, wherein the locking means are
arranged so that, upon loading a cartridge, a first abutment
surface is brought into an abutment engagement with the locking
means to bring them into an abutment engagement with a second
abutment surface, thus locking the bolt head, the locking means
being further arranged so that a predetermined time after the
discharge of the cartridge, the first abutment surface is withdrawn
from a locking engagement with the locking means, thus releasing
them from the locking abutment engagement with the second abutment
surface and allowing the bolt head to recoil.
4. The arrangement of claim 1, wherein at least one of the
following parameters can be changed to adjust the time delay,
during which the bolt head is locked, so as to allow the weapon to
discharge a cartridge having different charge characteristics or
projectile mass; the length of the timing surface; the mass of the
locking slide, the bolt head, the bolt assembly or the mass of the
entire weapon; the mechanical characteristics of a recoil spring
used to move the bolt assembly forwards after a recoil.
5. The arrangement of claim 4, wherein the following parameters can
be changed to adjust the time delay, during which the bolt head is
locked, so as to allow the weapon to discharge a cartridge having
different charge characteristics or projectile mass, in the
following manner; increasing the length of the timing surface to
allow for larger charge to be used; decreasing the mass of the
locking slide, the bolt head, the bolt assembly or the mass of the
entire weapon to allow for larger charge to be used; to reduce the
spring constant of the recoil spring to allow for larger charge to
be used.
6. The arrangement of claim 1, wherein the firing pin is arranged
to be able to discharge a cartridge only if the bolt head is
substantially in a locked configuration.
7. The arrangement of claim 6, wherein the firing pin is arranged
to protrude through an opening in the bolt head so that, when the
bolt head is not in a locked configuration, the firing pin is
unable to reach the cartridge and effect a discharge.
8-15. (canceled)
16. A locking arrangement for a bolt head of a recoil operated
firearm having a barrel; wherein in locked configuration, the
locking arrangement is adapted to retain the bolt head of the
firearm in abutting engagement with the barrel for a predetermined
time delay subsequent to discharge of the firearm; the locking
arrangement comprising at least one lug pivotally attached to the
bolt head; the at least one lug being operable between a first
retracted unlocked position and a second extended locking position;
the locking arrangement further comprising a locking slide provided
with a timing surface such that when the firearm is in a loaded and
cocked condition the timing surface retains the at least one lug in
the second locking position; the locking arrangement being such
that the length of the timing surface determines the delay between
the discharge and unlocking of the at least one lug, as the locking
slide is subjected to recoil induced movement relative the bolt
head, wherein the locked configuration of the locking arrangement
is adapted to retain a cartridge in the cartridge chamber of the
firearm; the predetermined time delay being sufficient for pressure
to drop in the barrel of the firearm, thereby to minimize the
ingress of gasses and other foreign material into the firing
mechanism of said firearm.
17. The locking arrangement of claim 16, wherein the bolt head of
the firearm is adapted for sliding movement in a cylindrical action
body housing the firing mechanism; the action body coaxial being
with the barrel of the firearm.
18. The locking arrangement of claim 16, wherein the at least one
pivotally attached lug of the bolt head is biased into the
retracted unlocked position when disengaged from said timing
surface.
19. The locking arrangement of claim 16, wherein the action body is
provided with an annular recess; a wall of the recess adapted to
engage with the at least one lug when the at least one lug is in
the second extended locking position.
20. The locking arrangement of claim 19, wherein the locking slide
is adapted for sliding movement in the cylindrical action body; the
locking slide being biased into a forward position within the
action body by a recoil spring; forward sliding movement of the
locking slide firstly driving the bolt head to the abutting
engagement with the barrel, and secondly engaging with the at least
one lug to pivotally rotate the lug into the second extended
locking position with the wall of the annular recess.
21. The locking arrangement of claim 16, wherein, subsequent to a
discharge, a rearward sliding movement of the locking slide is
communicated to the bolt head, once the at least one lug has
disengaged from the timing surface, such that the bolt head is
retracted rearwards from its abutting engagement with the
barrel.
22. The locking arrangement of claim 16, wherein a firing pin of
the firearm operates along apertures in the bolt head and the
locking slide; the length of the firing pin arranged so that
engagement of the locking pin with a primer of a cartridge is
prevented unless the locking slide is in the forward position with
the bolt head locked in the abutting engagement with the
barrel.
23. A bolt head locking arrangement of claim 1, wherein the
unlocking and/or the recoil of the bolt head is affected by
utilising gas pressure generated in the barrel of the firearm at
discharge, either by a gas tube providing blow-back of the slide,
or a connecting rod operated by a gas actuated piston.
24. A bolt head locking arrangement of claim 1, wherein the barrel
is slidingly mounted, so that the unlocking and/or the recoil of
the bolt head is facilitated by the recoil of the barrel.
25. A bolt head locking arrangement of claim 1, wherein the firearm
is a single shot or a pump action manually operated firearm and
wherein the unlocking and/or the recoil of the bolt head is
affected manually.
26. The arrangement of claim 2, wherein the firing pin is arranged
to be able to discharge a cartridge only if the bolt head is
substantially in a locked configuration.
27. The arrangement of claim 3, wherein the firing pin is arranged
to be able to discharge a cartridge only if the bolt head is
substantially in a locked configuration.
28. The arrangement of claim 4, wherein the firing pin is arranged
to be able to discharge a cartridge only if the bolt head is
substantially in a locked configuration.
29. The arrangement of claim 5, wherein the firing pin is arranged
to be able to discharge a cartridge only if the bolt head is
substantially in a locked configuration.
Description
TECHNICAL FIELD
[0001] The present invention relates to a locking arrangement for a
weapon. In particular, the invention relates to a locking/unlocking
arrangement for the bolt head of a firearm.
BACKGROUND OF THE INVENTION
[0002] The problem associated with foreign matter penetrating the
internal mechanisms of a firearm during the discharge of a
cartridge is well known in the weapon industry. The foreign matter
in question includes various gases and particulates released during
the discharge, as well as other contaminants, such as water
vapour.
[0003] To alleviate or ameliorate this problem, various systems
have been designed to impose a time delay between the discharge of
the cartridge and the release of the bolt head, thus minimising the
amount of foreign matter penetrating the inside of the weapon
during the cartridge discharge. Some of these systems rely solely
on the mass of the bolt head and the spring constant of the
associated recoil spring to resist the initial gas pressure of the
cartridge discharge. Other systems have a dedicated gas tube, which
the gas pressure has to traverse before reaching the bolt head,
thus creating a time delay between the cartridge discharge and the
recoil of the bolt head. Yet other arrangements use a toggle which
the gas pressure has to break before it can propagate inside the
weapon. All of these systems are somewhat complex and
inefficient.
[0004] U.S. Pat. No. 4,301,712, by Cristina discloses a hammer lock
which locks the hammer of the weapon, thus preventing opening of
the weapon bridge until bridge pressure drops to a residual safe
level. However, the locking mechanism disclosed in this patent is
based on an abutment engagement which is configured so as to
resists the gas pressure initially, but to be overcome at a later
stage. Because of this, and since both the locking and the
unlocking of this locking arrangement depend on a single abutment
engagement, it is believed that this engagement offers only a
partial lock that allows some gas pressure to penetrate even at the
initial stages of the discharge.
[0005] GIAT FAMAS assault rifle, on the other hand, employs a delay
lever interposed between the bolt itself and the bolt carrier. When
a cartridge is discharged, the bolt begins to move back under the
pressure. However, at the initial stages, when the pressure is
high, the delay lever transforms the short movement of the bolt
into the longer movement of the bolt carrier, thus delaying the
opening of the bolt. However, this system is also too complex and
offers only partial locking.
[0006] Some other prior art such as U.S. Pat. No. 3,998,126 by
Rudd, U.S. Pat. No. 4,232,583 by Harrison and WO 2005/031242 by
Abdullaev et al also utilise delay mechanisms that slow down the
bolt head after a cartridge is discharged to minimise the
penetration of pressure caused by the discharge into the action
body. This prior art utilise components such as delay rollers, cam
mechanisms and the like that are of complicated design and
manufacture and readily prone to wear.
[0007] U.S. Pat. No. 4,604,942 by Benelli discloses a bolt head
that is positively locked for a predetermined time after a loaded
cartridge is discharged. However, the bolt head must be rotated (or
twisted) to become unlocked. The bolt head has two projections
which in conjunction with associated grooves of the barrel comprise
a locking means. A disadvantage of this locking means is that
fouling, such that caused by debris or dirt entering the breech may
result.
[0008] Accordingly, it would be advantageous if a relatively simple
and reliable system is designed which can lock positively the bolt
head of a firearm for a particular duration of time after a
cartridge discharge, so as to minimise the penetration of discharge
generated substances into the firing mechanism of the weapon during
and immediately after the discharge.
SUMMARY OF THE INVENTION
[0009] According to a first aspect, the bolt head locking
arrangement for a recoil operated weapon where projectile is
expelled by discharging a cartridge, the weapon comprising a
longitudinal action body, a longitudinal barrel, the barrel being a
part of or axially attached to the action body, and a bolt
assembly, the bolt assembly being slidable within the action body
so as to affect at least one of; loading cartridges in the barrel
for discharging, discharging cartridges and extracting discharged
cartridges; the bolt assembly comprising a bolt head, a locking
slide and a firing pin, at least some of which being arranged for
moving with respect to each other, wherein the arrangement further
comprises locking means arranged so that, upon loading a new
cartridge for discharging, the locking means positively lock the
bolt head such that, for a predetermined amount of time after the
loaded cartridge is discharged, the locked bolt head stops the
cartridge from retreating into the action body, thus eliminating
the penetration of pressure caused by the discharge into the action
body, the locking means is substantially in an in-line
configuration with the bolt assembly, and said locking means are
arranged so that the recoil momentum of the weapon, caused by the
discharge, is used for unlocking the bolt head, wherein the locking
means are arranged so that, upon discharge of the cartridge, the
locking slide recoils backwards and, once the bolt head is
unlocked, the inertia of the locking slide facilitates the recoil
of the bolt head.
[0010] Preferably, said locking means are arranged so that, after
the bolt head is unlocked, a residual of the gas pressure formed
during the discharge is used for assisting with the recoil of the
bolt head.
[0011] Preferably, said locking means are arranged so that, upon
loading a cartridge, a first abutment surface is brought into an
abutment engagement with the locking means to bring them into an
abutment engagement with a second abutment surface, thus locking
the bolt head, the locking means being further arranged so that a
predetermined time after the discharge of the cartridge, the first
abutment surface is withdrawn from a locking engagement with the
locking means, thus releasing them from the locking abutment
engagement with the second abutment surface and allowing the bolt
head to recoil.
[0012] Preferably, said locking slide comprises a timing surface of
predetermined length and the locking means comprise at least one
locking lug that is engageable with the timing surface so as to
move between open and closed configuration, wherein in the closed
configuration the at least one lug is located within the
cross-sectional area of the bolt head to allow the sliding movement
of the head within the action body, while in open configuration the
at least one lug extends beyond this cross-sectional area to abut
with an abutment surface of the action body and prevent rearward
movement of the bolt head, wherein in use;
[0013] when the bolt assembly is moved forward to load a cartridge,
the locking slide moves with respect to the bolt head so that the
timing surface engages the at least one lug to push it into an open
configuration, so that when the bolt head is moved fully forwardly,
the bolt head is locked in a sealing engagement with the sealing
inner surface of the barrel and in an abutment engagement with the
abutment surface of the action body; and
[0014] upon discharging the cartridge, the locking slide moves
backwards, causing the entire predetermined length of the timing
surface to withdraw from its engagement with the at least one lug
and allow the at least one lug to move into closed configuration,
thus unlocking the bolt head and allowing it to recoil.
[0015] Preferably, at least one of the following parameters can be
changed to adjust the time delay, during which the bolt head is
locked, so as to allow the weapon to discharge a cartridge having
different charge characteristics or projectile mass;
[0016] the length of the timing surface;
[0017] the mass of the locking slide, the bolt head, the bolt
assembly or the mass of the entire weapon;
[0018] the mechanical characteristics of a recoil spring used to
move the bolt assembly forwards after a recoil.
[0019] Preferably, said following parameters can be changed to
adjust the time delay, during which the bolt head is locked, so as
to allow the weapon to discharge a cartridge having different
charge characteristics or projectile mass, in the following
manner;
[0020] increasing the length of the timing surface to allow for
larger charge to be used;
[0021] decreasing the mass of the locking slide, the bolt head, the
bolt assembly or the mass of the entire weapon to allow for larger
charge to be used;
[0022] to reduce the spring constant of the recoil spring to allow
for larger charge to be used.
[0023] Preferably, said firing pin is arranged to be able to
discharge a cartridge only if the bolt head is substantially in a
locked configuration.
[0024] Preferably, said firing pin is arranged to protrude through
an opening in the bolt head so that, when the bolt head is not in a
locked configuration, the firing pin is unable to reach the
cartridge and effect a discharge.
[0025] According to a second aspect, the method for locking and
unlocking a bolt head in a recoil operated weapon which expels
projectiles by discharging a cartridge, where at least one of
loading cartridges for discharging, discharging cartridges and
extracting discharged cartridges is assisted by a bolt head
assembly including a bolt head, the method comprising the step of
locking, upon loading a new cartridge for discharging, the bolt
head in a substantially in-line configuration such that, for a
predetermined amount of time after the loaded cartridge is
discharged, the locked bolt head prevents the cartridge from
retreating into the action body, thus eliminating the penetration
of pressure caused by the discharge into the action body, and the
recoil momentum of the weapon, caused by the discharge, is used for
unlocking the bolt head, and said method further comprising the
step of allowing a member of the bolt head assembly, the member
being engageable with the bolt head, to recoil, upon discharge of
the cartridge, the inertia of the member being used to, upon
unlocking of the bolt head, facilitate the recoil of the bolt
head.
[0026] Preferably, after the bolt head is unlocked, a residual of
the gas pressure, formed during the discharge, is used for
assisting with the recoil of the bolt head.
[0027] Preferably, locking of the bolt head is arranged by
providing a first abutment surface that, upon loading a cartridge,
is brought into an abutment engagement with locking means to bring
them into an abutment engagement with a second abutment surface,
thus locking the bolt head, unlocking of the bolt head a
predetermined delay time after the discharge of the cartridge being
facilitated by withdrawing the first abutment surface from the
locking engagement with the locking means, thus releasing the
locking means from the locking abutment engagement with the second
abutment surface and allowing the bolt head to recoil.
[0028] Preferably, said method further includes the step of
arranging so that, after a discharge, the first abutment member
recoils immediately, so that its predetermined length defines the
duration of engagement between the first abutment surface and the
locking means, thus also defining the predetermined delay time of
the recoil of the bolt head.
[0029] Preferably, to allow the weapon to discharge a cartridge
having different charge characteristics or projectile mass, the
method comprises the step of adjusting the time delay, during which
the bolt head is locked, by changing at least one of the following
parameters;
[0030] the length of the timing surface;
[0031] the mass of the bolt head, the bolt assembly or the mass of
the entire weapon;
[0032] the mechanical characteristics of a recoil spring used to
move the bolt assembly forwards after a recoil.
[0033] Preferably, to allow the weapon to discharge a cartridge
having different charge characteristics or projectile mass, the
method comprises the step of adjusting the time delay, during which
the bolt head is locked, by changing at least one of the following
parameters in the following manner;
[0034] increasing the length of the timing surface to allow for
larger charge to be used;
[0035] decreasing the mass of the locking slide, the bolt head, the
bolt assembly or the mass of the entire weapon to allow for larger
charge to be used;
[0036] to reduce the spring constant of the recoil spring to allow
for larger charge to be used.
[0037] Preferably, said method further including the step of
arranging a cartridge to be discharged only if the bolt head is
substantially in a locked configuration.
[0038] Preferably, a firing pin is arranged to protrude through an
opening in the bolt head so that, when the bolt head is not in a
locked configuration, the firing pin is unable to reach the
cartridge and effect a discharge.
[0039] According to a third aspect, there is provided a locking
arrangement for a bolt head of a recoil operated firearm having a
barrel; wherein in locked configuration, the locking arrangement is
adapted to retain the bolt head of the firearm in abutting
engagement with the barrel for a predetermined time delay
subsequent to discharge of the firearm; the locking arrangement
comprising at least one lug pivotally attached to the bolt head;
the at least one lug being operable between a first retracted
unlocked position and a second extended locking position; the
locking arrangement further comprising a locking slide provided
with a timing surface such that when the firearm is in a loaded and
cocked condition the timing surface retains the at least one lug in
the second locking position; the locking arrangement being such
that the length of the timing surface determines the delay between
the discharge and unlocking of the at least one lug, as the locking
slide is subjected to recoil induced movement relative the bolt
head.
[0040] Preferably, said locked configuration of the locking
arrangement is adapted to retain a cartridge in the cartridge
chamber of the firearm; the predetermined time delay being
sufficient for pressure to drop in the barrel of the firearm,
thereby to minimize the ingress of gasses and other foreign
material into the firing mechanism of said firearm.
[0041] Preferably, said bolt head of the firearm is adapted for
sliding movement in a cylindrical action body housing the firing
mechanism; the action body coaxial being with the barrel of the
firearm.
[0042] Preferably, said at least one pivotally attached lug of the
bolt head is biased into the retracted unlocked position when
disengaged from said timing surface.
[0043] Preferably, said action body is provided with an annular
recess; a wall of the recess adapted to engage with the at least
one lug when the at least one lug is in the second extended locking
position.
[0044] Preferably, said locking slide is adapted for sliding
movement in the cylindrical action body; the locking slide being
biased into a forward position within the action body by a recoil
spring; forward sliding movement of the locking slide firstly
driving the bolt head to the abutting engagement with the barrel,
and secondly engaging with the at least one lug to pivotally rotate
the lug into the second extended locking position with the wall of
the annular recess.
[0045] Preferably, subsequently to a discharge, a rearward sliding
movement of the locking slide is communicated to the bolt head,
once the at least one lug has disengaged from the timing surface,
such that the bolt head is retracted rearwards from its abutting
engagement with the barrel.
[0046] Preferably, a firing pin of the firearm operates along
apertures in the bolt head and the locking slide; the length of the
firing pin arranged so that engagement of the locking pin with a
primer of a cartridge is prevented unless the locking slide is in
the forward position with the bolt head locked in the abutting
engagement with the barrel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] A preferred embodiment of the invention will now be
described, by way of example only and with reference to the
accompanying drawings wherein:
[0048] FIG. 1 is a schematic cross-sectional side view of a recoil
delay arrangement for a blowback or recoil operated weapon,
according to the invention, the weapon being cocked, locked up and
ready to fire.
[0049] FIG. 2 is a schematic cross-sectional side view of the
arrangement of FIG. 1, wherein the weapon is shown after firing, in
the initial stage of a recoil.
[0050] FIG. 3 is a schematic cross-sectional view of the
arrangement of FIGS. 1 and 2, wherein the bolt head has just been
unlocked and the bolt assembly is about to recoil.
[0051] FIG. 4 is a schematic cross-sectional side view of the
arrangement of FIGS. 1 to 3, wherein the bolt assembly is partially
recoiled.
[0052] FIG. 5 is a schematic cross-sectional top view of the weapon
of FIGS. 1 to 4, showing the cocking handle and the magazine.
PREFERRED EMBODIMENTS OF THE INVENTION
[0053] In the preferred embodiment, the recoil operated weapon is
in the form of firearm 1, a section of which is illustrated in
FIGS. 1 to 5. The illustrated section of the firearm includes
barrel 2 with sights, grips and heel plate (not shown). A
cylindrical action body 3 is threaded to barrel 2. The firearm also
includes a trigger assembly 4 having sear 5 that is screwed to
action body 3. Magazine connection, ejector slots and stock tube,
not shown, are fitted to action body 3. Bolt assembly 6 consists of
the firearm's cocking handle 7 (visible in FIG. 5), bolt head 8 and
locking slide 9. Bolt head 8 includes spring washers 10, spring
washer stop 11 and firing pin 12. Recoil return spring 13,
polyurethane stop 14, rear recoil stop plug 15, its locking spring
pin 16, locking lug 17, cartridge ejector 18 and extractor 19 are
also part of bolt assembly 6. The bolt assembly is held together by
cocking pin 20 and is arranged for sliding movement within action
body 3.
[0054] To use the weapon, a trigger safety lever (not shown) is
switched to "safe", the magazine with the cartridges is snapped and
cocking handle 7 is pulled back. Upon release of handle 7, recoil
spring 13 forces bolt assembly 6 forward, taking a cartridge from
the magazine and loading it into cartridge chamber 21 in barrel 2.
The firearm is thereby cocked, but is still on safety lock.
[0055] During the above forward movement, lock-up of bolt assembly
6 occurs when the recoil return spring 13 pushes front face of bolt
assembly 6 hard against the barrel chamber face 25. Locking slide 9
is pushed by recoil spring 13 into engagement with bolt head
locking lug 17, which is pivoted outwardly from behind the bolt
head 8 so as to engage with an angled wall 23 of an annular recess
in the action body 3, thus preventing rearward movement of the bolt
head. The forward movement also cocks the firing pin by the
compression of spring washers 10 as cocking pin 20 is arrested by
the cocking stop 24 of sear 5.
[0056] In the locked position shown in FIG. 1, where the bolt head
locking lug 17 pushes against angled wall 23 of the annular recess,
the bolt head is positively sealed against the inner face 25 of
barrel 2. The locking slide 9 under urging of the recoil spring 13
is then at its maximum forward position, limited by the shoulder of
the timing surface engaging the outer end of the locking lug 17.
When the firearm is fired, bolt head 8 is released and allowed to
recoil only after a predetermined time delay, thus eliminating the
penetration of foreign substances, such as discharge gasses and
water vapour, into the action body during the cartridge
discharge.
[0057] The process by which the time delay is implemented will now
be explained. In order to fire the rifle, the safety lock must be
unlocked and the trigger actuated to release firing pin 12. Firing
pin 12 is driven forward by the compressed spring washers 10 to
indent the cartridge primer and make it ignite, thus discharging
the cartridge. When the cartridge is discharged, during the initial
stage of recoil while the bullet moves up the barrel, locking slide
9 is driven rearwards by the force of recoil as shown in FIG. 2.
However, locking lug 17 initially prevents the rearward movement of
bolt head 8. Only after the entire length of timing surface 26 is
withdrawn from its engagement with locking lug 17, is the lug
allowed to pivot back into the main bolt head body as, because of
the rearward pressure on the bolt head, the angled face of the
locking lug slides against angled wall 23. Thus, the pivoting
movement of the lug into closed configuration allows the whole bolt
assembly to recoil, as shown in FIG. 3 and FIG. 4. The time delay
is typically adjusted so that the bolt head remains locked until
the bullet exits the barrel and the pressure in the barrel reaches
a desired low level.
[0058] The force driving the recoil of the bolt head, after it is
unlocked, is the backwards inertia of the recoiling locking slide
9. At a particular point during its backward movement after the
discharge, the slide engages locking pin 20, so that the movement
is communicated to bolt head 8 as the firing pin is pulled
backwards against spring washers 10, which in turn push against
washer reaction ring 11. From this point on, the locking slide and
the bolt head recoil together. Thus, the recoil of locking slide 9
is used to effect both the unlocking and the recoil of bolt head
8.
[0059] During the recoil of bolt assembly 6, the spent cartridge
case is extracted from the cartridge chamber 21 and is ejected
through a cocking handle slot (or alternative slot) as the bolt
assembly moves rearward. The bolt assembly then reaches the fully
recoiled position, with the recoil spring 13 and the polyurethane
stop being fully compressed. After bolt assembly 6 is stopped from
its rearward movement, it is then pushed forward by the compressed
recoil spring 13 and compressed polyurethane, picking up another
cartridge from the magazine and sliding said cartridge into the
weapon's cartridge chamber 21 in front of the bolt assembly.
[0060] Lock-up is again achieved in the same way as previously
described and the firearm is ready to fire single shot, burst or
automatic.
[0061] It is clear from the above description that the time delay,
after which the entire bolt assembly 6 is allowed to recoil, is a
function of the length of the timing surface 26. This length can be
varied to suit various types of ammunition. One example is if the
use of cartridges containing different charges or different
projectiles, is desired. In addition, other factors can also be
used to accommodate such a change. Such factors are the strength of
the recoil return spring 13, the mass of the locking slide 9, the
total mass of bolt assembly 6, the mass and velocity of bullet, the
total mass of the weapon and whether or not residual gas pressure
is used to increase bolt assembly recoil movement. A larger
discharge is accommodated by using a longer delay surface, smaller
mass of the locking slide or the total mass of the bolt assembly,
or a smaller spring constant of the recoil spring.
[0062] In the above description the system was arranged so that the
backwards momentum of the weapon, caused by the discharge, is used
for unlocking the bolt head. However, a residual pressure from the
discharge can also be used to assist the recoil of the bolt head,
after it has been unlocked. One way to utilise some of the pressure
created during cartridge discharge is by reducing the length of the
time delay surface to reduce the delay time in order to allow
unlocking of the system at different reference point with respect
to the time of cartridge discharge.
[0063] It has to be noted here that, strictly speaking the term
"recoil" refers to the backward movement of the weapon upon
discharge of a cartridge. Thus, the delayed backwards movement of
the bolt head is not strictly a "recoil". However, since this
backward movement is ultimately caused by the recoil of the weapon,
for simplicity and succinctness, this delayed backward movement of
the bolt head here has also been called "recoil". Similarly,
although the arrangement that is the subject of this invention
relates to both the locking and the unlocking of the bolt head, for
simplicity and easy of reference, it has been simply referred to as
"locking arrangement".
[0064] An additional feature of the above described arrangement is
that firing pin 12 protrudes through an opening in bolt head 8 and
is configured to protrude and be able to reach and discharge the
cartridge only if the bolt head is substantially in a locked
configuration. It will be apparent from FIG. 2 in particular, that
the firing pin 12 is of such a length that it would be arrested by
the cocking stop 24 reaching the forward limit of the slots in
locking slide 9, unless slide 9 is in the locking position of FIG.
1. This ensures that the firearm is fired only if bolt assembly 6
is substantially locked, thus providing a consistent time
delay.
[0065] Another feature of the disclosed system includes the fact
that the sliding elements of the bolt assembly are designed to lock
in line so that all clearances between abutting elements of the
bolt assembly are minimised when the bolt head comes into the
locked position. This allows large clearance between the sliding
adjacent surfaces of the bolt assembly and the action body while
the bolt is moving inside the action body. Because of this, the
system can operate with dirt and water inside the body and bolt
area. Also, in this preferred embodiment of the invention, the
in-line lock-up system does not have to have gas operated blow back
pistons to move the bolt so as to turn the locking bolt head. Thus,
there is no fouling of these parts, as they are not required to
operate this system.
[0066] It should be understood that as the bolt head comes into the
locked position the bolt assembly may cock the weapon such that it
may fire again.
[0067] Further advantages of the system relate to the fact that the
system has minimum number of parts, is easy to machine and simple
to maintain. The system also offers substantial flexibility in
relation to amendments to the structure of the firearm. For
example, the cocking handle can be on the left or right, the
magazine and cartridge ejection slots can be radially positioned
almost anywhere and no separate hammer is needed to actuate the
firing pin.
[0068] It is obvious from the above description, that the disclosed
arrangement offers a relatively simple and reliable system for
locking positively the barrel of a firearm for a particular length
of time after a cartridge discharge, thus minimising the
penetration of foreign substances into the firing mechanism of the
weapon during and immediately after the discharge.
[0069] It should be appreciated that the disclosed arrangement is
not limited to the particular embodiments disclosed here, but also
covers other arrangements using similar concepts. For example,
while the preferred embodiment uses a single locking lug, two or
more lugs can also be used. In addition, the lugs can be moved into
locking engagement not only by the locking slide, but by any other
part of the weapon that has a suitable relative movement with
respect to the bolt head during the recoil.
[0070] Furthermore, although the above description of the invention
relates to recoil operated firearms in which the differential
masses of the firearm, as a whole, and the locking slide are
utilised to effect the unlocking delay, the principles of the
timing surface of the invention may equally be applied with other
means of moving the locking slide.
[0071] Thus, for example, the activation of the locking slide
rearwards may be effected by utilising the gas pressure generated
in the barrel of the firearm at discharge, either by a gas tube
providing blow-back of the slide, or a connecting rod operated by a
gas actuated piston.
[0072] Again the movement of the slide may also be effected in
firearms in which the barrel is slidably mounted and in which the
recoil of the barrel rather than that of the firearm, as a whole,
provides the recoil force driving the locking slide.
[0073] Finally, the principles of the timing surface may be applied
to manually operated firearms, either single shot or pump action,
where the slide is manually pulled back after discharge, then
driven forward at reload to re-lock the bolt head.
[0074] The terms "comprising" and "including" (and their
grammatical variations) as used herein are used in the inclusive
sense of "having" and not in the exclusive sense of "consisting
only of".
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