USOO8726560B2

(12) Unlted States Patent (10) Patent N0.: US 8,726,560 B2

(54) CHAMBER INSERT LOCK INSTALLED 4,098,016 A * 7/1978 Foote .............................. .. 42/16
WITHIN AN AR_15/16 BARREL EXTENSION 4,169,329 A * 10/1979 Atchisson ~~~~~~~~~~~~~~~~~~~~~~~ ~~ 42/16
4,194,314 A 3/1980 FOOte
FOR LOCATING AND REDUCING 4,617,749 A * 10/1986 Jurek .............................. .. 42/16
MOVEMENT OF AN ASSOCIATED SUB 4,955,157 A * 9/1990 Brighton et a1. 42/77
CALIBERACTION 6,050,170 A * 4/2000 Guiette etal. 89/29
6,293,040 B1* 9/2001 Luth .......................... .. 42/7501
(75) Inventors: John L. Overstreet, Fayette, MO (US);
- - _ , ,
* it?“ et a1~
e 1n ............................ ..
89/128
Charles C“ Kelly’ KlrksYlne’ 7,444,775 B1 >1< 11/2008 Schuetz “““““““““““ H 42/76‘01
Jordan Bowles, Columb1a,
. . MO (US); 7 , 798 , 045 B1 9/2010 F-1tzpatr1ck
- et al.
Tys‘fn BrafEhaW’ Klrkswlles MO (Us); 7,849,777 B1 12/2010 Zedrosser
Cralg Pudll, Boom/?le, MO (US); Taz 8,316,755 B2* 11/2012 Overstreet 6131. ............ .. 89/179
B. Pfefer,Ashland, MO (US) 8,397,416 B2* 3/2013 Laney et a1. ............... .. 42/7502
8,453,367 B2* 6/2013 Overstreetetal. . 42/108
(73) Assignee: 22 Evolution LLC, Columbia, MO (US) 8,505,428 B2 * 55/2013 Overstreet et 31~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~ 89/14
8,590,199 B2* 11/2013 Overstreetetal. . .. 42/69.02
(*) Notice: Subject to any disclaimer, the term of this * {mull """""""""""""" " 89/128
~ ~ auc

Patent 15 mended or adluswd under 35 2011/0252685 A1* 10/2011 Overstreet 6131. .............. .. 42/16
U.S.C. 154(b) by 548 days.
(Continued)
(21) Appl.No.: 13/070,023
Primary Examiner * Benjamin P Lee
(22) Filed: Mar. 23, 2011
(74) Attorney, Agent, or Firm *Gifford, Krass, Sprinkle,
(65) Prior Publication Data Anderson & Citkowski, P.C.; Douglas J. McEvoy
US 2011/0265638 A1 Nov. 3, 2011
(57) ABSTRACT
Related US. Application Data
(60) Provisional application No. 61/328,765, ?led on Apr. The present invention teaches an insert locking mechanism
28, 2010. incorporated into a sub caliber action device, installable
Within an upper receiver of anAR- 1 5 type ?rearm, and Which
(51) Int. Cl. interfaces With an upper receiver mounted forward assist for
F41A 21/10 (2006.01) use With such as .22 caliber ammunition and in order to
(52) US. Cl. eliminate movement or play of the chamber insert adaptor
USPC ............................... .. 42/77; 42/69.02; 89/128 associated With the substituted sub caliber action. The mecha
(58) Field of Classi?cation Search nism includes a generally cylindrical shaped body supported
USPC ........................ .. 42/77, 106, 69.02, 14; 89/29 upon the action and exhibiting a plurality of radially project
See application ?le for complete search history. ing and circumferentially extending lugs Which are con?g
ured to mate and seat Within a plurality of grooves circum
(56) References Cited ferentially arrayed Within a barrel de?ned in the upper
U.S. PATENT DOCUMENTS receiver.

3,776,095 A * 12/1973 Atchisson ..................... .. 89/128

(56) References Cited 2011/0277368 A1* 11/2011 Overstreet et al. ............ .. 42/108
2012/0005931 A1* 1/2012 Kelly et al. ..................... .. 42/14
U.S. PATENT DOCUMENTS
2011/0252957 A1 * 10/2011 Overstreet et a1. ,,,,,,,,,,,, ,, 89/128 * Cited by examiner
US. Patent May 20, 2014 Sheet 1 0f 10 US 8,726,560 B2

FIG. 1
US. Patent May 20, 2014 Sheet 2 0f 10 US 8,726,560 B2
US. Patent May 20, 2014 Sheet 3 0f 10 US 8,726,560 B2

30
28

18
FIG. 5
US. Patent May 20, 2014 Sheet 4 0f 10 US 8,726,560 B2
US. Patent May 20, 2014 Sheet 6 6f 10 US 8,726,560 B2
US. Patent May 20, 2014 Sheet 7 0f 10 US 8,726,560 B2
US. Patent May 20, 2014 Sheet 8 0f 10 US 8,726,560 B2
US. Patent May 20, 2014 Sheet 9 0f 10 US 8,726,560 B2

FIG. 17A 66

>

70
68 (&
US. Patent May 20, 2014 Sheet 10 0f 10 US 8,726,560 B2

FIG. 17B
 US 8,726,560 B2
1 2
CHAMBER INSERT LOCK INSTALLED The bolt further exhibits a rearward projecting support
WITHIN AN AR-15/16 BARREL EXTENSION sleeve including an open interior for receiving and seating an
FOR LOCATING AND REDUCING opposing guide rod associated with a further mounting loca
MOVEMENT OF AN ASSOCIATED SUB tion of the receiver plate and in order to maintain in assembled
CALIBER ACTION fashion the forward assist adaptor. The forward assist adaptor
further exhibits a generally semi-circular cross sectional
CROSS-REFERENCE TO RELATED shape with a plurality of scales along an extending side in
APPLICATIONS communication with a forward engaging pawl of the forward
assist. An additional variant includes sub-caliber action
This Application claims the bene?t of US. Provisional secured to an upper receiver barrel by a spring loaded ball
Application 61/328,765 ?led on Apr. 28, 2010. detent locking within a groove extending around a circum
ference of such as a dedicated .22 barrel.
FIELD OF THE INVENTION
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention discloses an upper receiver install
able sub caliber action device including a modi?ed bolt Reference will now be made to the attached drawings,
assembly incorporating a forward positioned and seating when read in combination with the following detailed
chamber insert for use with such as an AR-15/M16 type
description, wherein like reference numerals refer to like
?rearm. The chamber insert exhibits radially projecting lugs
which seat within interiorly communicating grooves estab 20 parts throughout the several views, and in which:
lished in the barrel extension in order to remove any degree of FIG. 1 is an illustration of the chamber insert lock incor
looseness or play of the action. A further variant of the cham porated into a sub caliber action according to the present
ber insert lock is con?gured to ?t within a dedicated sub invention;
caliber action and essentially acts as a link between the collar FIG. 2 is a similar illustration to FIG. 1 in which the cycling
and barrel associated with a standard AR1 6/M1 6 extension. A 25 bolt is depicted in a rearwardly displaced condition upon the
yet further variant discloses a sub-caliber action secured to an associated ?xed receiver plate and the insert lugs are depicted
upper receiver barrel by a spring loaded ball detent locking a pre-seated distance from an illustrated portion of the upper
within a groove extending around a circumference of such as receiver depicting aligning barrel extension grooves;
a dedicated .22 barrel. FIG. 3 is a succeeding illustration to FIG. 2 in which the
30 insert lugs seat within the barrel receiver grooves in a most
BACKGROUND OF THE INVENTION forward displaced condition of the sub caliber action;
FIG. 4 is a sectional illustration of the chamber insert with
Modi?cation of an exiting AR-15/M16 type ?rearm, such locking feature dismounted from the sub caliber action;
as in order to accept a sub caliber action, often results in the FIG. 5 is an overall perspective view of the sub caliber
associated chamber insert adaptor exhibiting an incremental 35
action as generally depicted in FIG. 3 illustrating the full
amount of inter movement or play with respect to the barrel
length of the receiver plate and rear engaging forward assist,
extension of the ?rearm upper receiver. Such movement has
and which depicts the barrel receiver in solid with partial
been found to impede performance of the ?rearm assembly
during loading and extracting of cartridges. cutaway within which the insert lugs are locked;
40 FIG. 6 is a further cutaway view illustrating a projecting
SUMMARY OF THE INVENTION arm associated with the insert rotated to a downward (6
o’clock) seating position against receiver housing;
The present invention teaches an insert locking mechanism FIGS. 7A-B illustrate end views of FIG. 5 in which insert
incorporated into a sub caliber action device, installable is illustrated in pre-spaced and post displaced and rotated/
within an upper receiver of an AR- 1 5 type ?rearm, and which 45 locked positions relative to the housing;
interfaces with an upper receiver mounted forward assist for FIG. 8 is an illustrative perspective of partial upper and
use with such as .22 caliber ammunition and in order to lower receiver components in an pre-assembled condition
eliminate movement or play of the chamber insert adaptor with the sub-caliber action pre-installed within the upper
associated with the substituted sub caliber action. The mecha receiver;
nism includes a generally cylindrical shaped body supported 50 FIG. 9 is a similar illustration to FIG. 8 in which the sub
upon the action and exhibiting a plurality of radially project caliber action is depicted without the upper receiver;
ing and circumferentially extending lugs which are con?g FIG. 10 is an enlarged linear perspective of the upper
ured to mate and seat within a plurality of grooves circum receiver underside and depicting the barrel extension grooves
ferentially arrayed within a barrel de?ned in the upper which seat the chamber insert lugs;
receiver. 55 FIG. 11 is a further overall view of an upper receiver and
The body further exhibits such as a single rearward posi further depicting in partially removed fashion a rear installing
tioned and further outwardly projecting lever type feature charging handle in combination with the sub caliber action;
which is rotated downwardly to seat against a location of the FIGS. 12-16 depict a series of perspective exploded and
upper receiver. The action further includes a generally elon assembled views of a further variant of chamber insert lock
gated receiver plate exhibiting a generally lengthwise extend 60 incorporated into a dedicated sub caliber action according to
ing notched interior established between extending sides, the the present inventions;
notched interior seating a bolt and a forward assist adaptor in FIG. 17 is an exploded view of a further variant of sub
reciprocating fashion along the receiver plate between an caliber action secured to an upper receiver barrel by a spring
end-most location and a forward secured chamber adaptor. loaded ball detent locking within a groove extending around
Additional features include the cylindrical shaped body being 65 a circumference of such as a dedicated .22 barrel;
supported forward of the bolt in seating fashion upon the FIG. 17A is an assembled and side cutaway view of the
chamber adaptor. assembly shown in FIG. 17; and
 US 8,726,560 B2
3 4
FIG. 17B is a further side plan view of the assembly in FIG. ponent 10 can be incorporated into any sub caliber action
17A in partial cutaway and depicting a portion of the bolt to device which may or may not incorporate forward assist
forward chamber adaptor interface. functionality.
The con?guration of the bolt assembly 18 is further such
DETAILED DESCRIPTION OF THE PREFERRED that a rearward projecting support sleeve 28 includes an open
EMBODIMENTS interior for receiving and seating an opposing guide rod 30
(again FIGS. 5 and 9) associated with a further mounting
Referring now to the following illustrations, the present location of the receiver plate 12 and in order to maintain in
invention discloses an upper receiver installable sub caliber assembled fashion the adaptorbolt subassembly 18 (such as is
action device including a modi?ed bolt assembly incorporat known as a .22 caliber adaptor bolt). Although not shown, a
ing a forward positioned and seating chamber insert for use main action coil spring is positioned between the sleeve 28
with such as anAR-15/Ml6 type ?rearm. The chamber insert and rod 30 to bias the bolt relative the receiver plate.
exhibits radially projecting lugs which seat within interiorly As is known, the bolt assembly is a mechanical part of the
?rearm upper receiver and which is seated within a barrel at a
communicating grooves established in the barrel extension in
location in which it blocks a rear of the associated chamber
order to remove any degree of looseness or play of the action.
during burning of the propellant. In semi-automatic ?rearms,
Referencing throughout the various drawings, and with such as is the case AR-15 type ?rearms, the bolt is caused to
initial reference to FIG. 1, illustrated at 10 is a generally cycle back and forth during each cartridge discharge cycle,
cylindrical shaped main body of a chamber insert lock incor propelled by recoil/expanding gas (backwards) or spring
porated into a sub caliber action according to the present 20 recoil (forwards) via a forward extending gas port and an
invention. The sub caliber action is illustrated throughout the upper and rear extending/rerouting of a gas tube for utiliZing
drawings and includes generally elongated receiver plate is the gas blowback to successively eject and reload (re-cham
shown at 12 and exhibits a generally lengthwise extending ber) a succeeding round.
notched or keyed interior, established between generally par Upon moving back, the bolt pushes the cartridge (not
allel extending sides 14 and 16 (see as best shown in FIG. 2 25 shown) from an attached magaZine (also not shown) and
and which also depicts inwardly facing protrusions estab pushes it into a ?rearm chamber established between the
lished along the inwardly facing and extending sides de?ning upper and lower assembled receivers. Upon successive dis
the notch for locating and seating the various adapter and bolt charge, and once the spent shell casing case is clear of the
components). chamber, an ejector component of the bolt ejects the casing
The notched interior of the receiver plate 12 is con?gured 30 from the receiver and out of the ?rearm (such as through a side
for seating the remaining components of the modi?ed bolt window of the upper receiver which exposes the ?ring cham
assembly in a generally stacked and assembly fashion. ber.
Among these are included each of a reciprocating bolt sub As is further known, the assembled sub caliber action is
inserted within a rear open end of an associated upper receiver
assembly 18 with side disposed extractor 20, a forward assist
35 portion (see as partially depicted at 32 in FIGS. 8 and 10) of
adapter 22, see in particular FIGS. 5 and 9, which is seated
the AR-15 ?rearm. Without further elaboration, additional
behind the bolt 18 and exhibits side disposed scales or edges
existing and interfacing features associated with the upper
23 for selectively being engaged by a forward assist plunger receiver include an underside accessible aperture (see as
24, and a forward-most projecting ?xed chamber adaptor 26. again shown in FIG. 10) de?ned in a lengthwise con?gured
In this fashion, the forward assist sub caliber action device 40 barrel portion (and which further exhibits a circumferentially
is mounted within the upper receiver portion of the AR-15 spaced plurality of radially con?gured and alternating ramps
type ?rearm (see FIG. 8 et seq.) and exhibits a forward most and recessed grooves, as depicted by grooves 34 separated by
engagement feature for contacting a speci?ed ridge or scale an alternating plurality of ramps 35), the upper receiver 32
23 of the adaptor component 22. In use, the forward assist being secured upon an associated lower receiver 36 (see
plunger 24 is used to manually close the sub caliber action and 45 FIGS. 8 and 9) and communicating magaZine and which,
is, in this sense an “emergency” feature in that, such as in upon installation, is in communication with the reciprocating
instances where the chamber gets dirty and/or if the action bolt subassembly 10.
spring is a little older and less springy, the bolt may fail to Additional existing features of the upper receiver 32
close all the way. include the provision of a forward assist housing 38 (FIG. 8)
As further depicted, the forward assist pushes on a selected 50 mounted in angularly extending and integrated fashion into a
location established along the plurality of side disposed rear housing location of the upper receiver 34 and which seats
ridges or scales 23 exhibited on the forward assist adaptor 22, the forward assist plunger 24. A charging handle 40 (see FIG.
these again termed “?sh scales” which are exhibited on the 11) is installed within an open rear of the barrel portion of the
side of the bolt carrier for enabling the bolt to be fully pushed upper receiver 32 and which assists in seating, supporting and
into the forward located chamber adaptor. As is further illus 55 removing of the sub caliber action within the upper receiver
trated, the forward assist plunger 24 on the upper receiver is 32.
manipulated via a push button con?guration found com As best depicted in the sectional illustration of FIG. 4, the
monly on M16 and AR-15 styled ri?es, and usually located chamber insert 10 with locking feature is shown dismounted
near the bolt closure such that, when depressed, the plunger from its otherwise installed position upon the sub caliber
will push the bolt carrier forward, ensuring that the bolt is 60 action, and in particular upon the forward projecting chamber
locked. The forward assist can also be used to close a bolt that adaptor 26. The generally cylindrical shaped insert 10 is
was gently let down, rather than released under full spring constructed of an appropriate metallic composition (such as
compression, such as in order to keep the noise of closing the without limitation including a brass construction) and exhib
bolt to a minimum. For purposes of the present invention, it its a plurality of forward positioned, radially projecting and
should be understood that the forward assist adaptor 22 is an 65 circumferentially arrayed lugs 42, each of which exhibits a
optional component for purposes of the variant depicted in speci?ed depth which, as will be further described, is
FIG. 5, with the further understanding that inset locking com intended to align with and nest or seat within the barrel
 US 8,726,560 B2
5 6
extension grooves 34 (again FIG. 10) associated with com feature 58. The barrel 54 further includes an inner nut 60,
municating inner barrel end of the upper receiver 32. As within which is interiorly formed a plurality of inner groove
shown, the insert 10 also depicts a single rearward positioned de?ning and circumferentially spaced ramp projections 62
and further outwardly/downwardly projecting lever type fea (compared to the inner ramps and grooves 34 in FIG. 10)
ture 44 which, upon assembly of the dedicated receiver, align and
FIG. 2 is a similar illustration to that depicted in FIG. 1 and offset with radially projecting lugs 56 of the dedicated insert
illustrates the reciprocating (or cycling) bolt 18 in a rear 46.
wardly displaced condition relative the associated receiver FIG. 14 illustrates a pre-assembled position of the dedi
plate and in which the circumferentially arrayed insert lugs 42 cated insert 46 located upon the end located support 50 and
are depicted a pre-seated distance from an illustrated portion prior to inserting of the inner supported extension 52 of the
of the upper receiver depicting aligning barrel extension 34 barrel 54. Proceeding to FIG. 15, an initial installation posi
grooves. Proceeding to FIG. 3, a succeeding illustration tion is shown in which the barrel 54 is assembled and the inner
depicts the insert lugs 42 seated within the barrel receiver disposed and groove de?ning ramp projections 62 align with
grooves 34 (see again in phantom) in a most forward dis and seat past the spaces de?ned between the circumferen
placed condition of the sub caliber action and associated with tially spaced lugs 56. With reference to FIG. 16, the dedicated
the insert 10 seated ?ush within the barrel receiver location insert 46 is rotated to align the lugs 56 behind the upper
depicted in FIG. 10, and with the forward most chamber extending ramped edges of the projections 62 de?ned in the
adaptor 26 extending through the barrel portion of the upper inner barrel nut 60.
receiver 32 in the manner shown in FIG. 3. Referring now to FIG. 17, an exploded view is shown of a
Proceeding to FIG. 5, an overall perspective view of the sub 20 further variant of a sub-caliber action 64 (again termed as a
caliber action as generally depicted in FIG. 3 illustrates the type of chamber lock de?ning a forward mounted component
full length of the receiver plate 12 and rear engaging forward of the receiver plate and for removing inter-movement or play
assist 24, and which further depicts a portion of the upper between the forward most mounted chamber adaptor (such as
(barrel) receiver 32 in solid with partial cutaway within which at 26) and the upper receiver barrel 66. In this variant, the
the circumferentially arrayed lugs 42 of the insert 10 are 25 chamber lock exhibits a generally barrel or collar shaped
locked. FIG. 6 is a further cutaway view illustrating the pro body (again at 64. A spring loaded ball detent is arranged
jecting lever 44 associated with the insert 10 which is rotated upon an inserting end of an engagement body, see at 68 as best
to a downward (6 o’clock) seating position relative to an inner shown in FIG. 17A, and which is pressed into a sleeve or
notched location 45 of a bolt hold open actuator subassembly aperture 70 within the action (or lock) body 64.
47 incorporated into the upper receiver housing to prevent the 30 The body 68 exhibits a generally elongated and three
insert/lock 10 from coming undone when the ri?e is dis dimensional shape and integrates a spring (not shown) which
charged. displaces an end supported ball detent, further shown at 72.
FIGS. 7A-B illustrate a pair of end views of FIG. 5 in which The body 68 is press ?t within the aperture 70 so that the ball
the insert 10 is illustrated in respective pre-spaced and post detent engages as shown, however it is further understood that
displaced and rotated/locked positions relative to the altemat 35 alternative variants can also incorporate a threaded engage
ing grooves 34 associated with the upper receiver housing 32. ment established between the detent body and the inner radi
FIG. 8 further provides an illustrative perspective of partially ally extending aperture in communication with the inserting
depicted upper 32 and lower 36 receiver components in an barrel 66. In this fashion, the ball 72 is biased in an inwardly
pre-assembled condition with the sub-caliber action pre-in and engaging fashion within a recessed (typically “V”
stalled within the upper receiver 32 and FIG. 9 a similar 40 shaped) groove 74 extending around a circumference of an
illustration to FIG. 8 in which the sub caliber action is inserting neck 76 of the barrel 66 (such as a dedicated .22
depicted without the upper receiver. barrel), the detent 72 further capable of being physically
In this fashion, the chamber insert 10 ?ts within the upper disengaged from the barrel 66 by exerting a reverse pulling
receiver barrel and is secured by the overall length ?t estab force to separate from the annular groove 74 or by otherwise
lished by the sub caliber action (see again mounting location 45 modifying the detent to retract from the groove in a static
upon which the insert 10 seats at a base of the forward pro position.
jecting chamber adaptor 26). In this manner, any extra space As further shown in FIG. 17A, the sub-caliber action 64
is occupied by the insert 10 and further so that the action exhibits a generally barrel collar shape which encircles an
receiver 12 (upon which the bolt 18 is repetitively cycled) is inserting annular neck portion 76 of the barrel 66. FIG. 17B is
maintained without any degree of looseness or play. As a 50 a further right side plan view of the assembly in FIG. 17A, in
result, an optimal degree of performance is realized during partial cutaway, and depicting a portion of the bolt 68 to
loading and extracting motion of the bolt 18 during each forward chamber adaptor interface also including the receiver
cartridge cycle. plate 12.
Referring to FIGS. 12-16, depicted are a series of perspec Having described my invention, other and additional pre
tive exploded and assembled views of a further variant of 55 ferred embodiments will become apparent to those skilled in
chamber insert lock, generally illustrated at 46 (as compared the art to which it pertains, and without deviating from the
to that shown at 10 in FIG. 1) and incorporated into a dedi scope of the appended claims.
cated sub caliber action (further referenced by receiver plate We claim:
48). The receiver plate 48 is shown without the bolt and 1. An insert locking mechanism incorporated into a sub
further illustrates, at a forward end, an end support 50 for 60 caliber action device installable within an upper receiver of an
seatingly receiving the insert lock 46 in assembled fashion AR-15 type ?rearm for use with at least .22 caliber ammuni
along with an inner extension portion 52 of associated upper tion, the action device including an elongated receiver plate
receiver barrel 54. seating a reciprocating bolt, said mechanism comprising:
As with the insert previously described at 10, the dedicated a generally cylindrical shaped body which is both sup
insert 46 exhibits a plurality of radially projecting and cir 65 ported upon and situated around a chamber adapter
cumferentially arrayed lugs 56 at a forward end combined mounted to a forward end of the receiver plate and pro
with a single rearward positioned and downwardly projecting jecting forwardly from the bolt, a plurality of radially
 US 8,726,560 B2
7 8
projecting and circumferentially extending lugs posi device within said upper receiver to remove any loose
tioned around a forward end of said cylindrical shaped ness between said action device and said upper receiver.
body which are con?gured to mate and seat within a 7. The action device as described in claim 6, said insert lock
plurality of grooves circumferentially arrayed within a further comprising a plurality of radially projecting and cir
con?gured inner end of a barrel portion of the upper cumferentially extending lugs around a forward end of said
receiver. cylindrical shaped body which are con?gured so as to be
2. The mechanism as described in claim 1, said body fur adapted to mate and seat within a plurality of grooves circum
ther comprising a rearward positioned and outwardly proj ect ferentially arrayed within the con?gured inner end of the
ing lever which seats within a notch associated with a bolt barrel.
hold open subassembly incorporated into the upper receiver. 8. The action device as described in claim 7, said body
3. The mechanism as described in claim 1, receiver plate further comprising a rearward positioned and outwardly pro
exhibiting a generally lengthwise extending notched interior jecting lever which seats within a notch associated with a bolt
established between extending sides, said notched interior hold open subassembly incorporated into the upper receiver.
seating a bolt and a forward assist adaptor in reciprocating 9. The action device as described in claim 6, further com
fashion along said receiver plate between an end-most loca prising a forward assist adaptor positioned rearwardly of said
tion and a forward secured chamber adaptor. bolt upon said receiver plate in likewise reciprocating fash
ion.
4. The mechanism as described in claim 3, said bolt further
comprising a rearward projecting support sleeve including an 10. The action device as described in claim 9, said bolt
open interior for receiving and seating an opposing guide rod further comprising a rearward projecting support sleeve
associated with a further mounting location of said receiver 20 including an open interior for receiving and seating an oppos
plate and in order to maintain in assembled fashion said ing guide rod associated with a further mounting location of
forward assist adaptor. said receiver plate and in order to maintain in assembled
5. The mechanism as described in claim 3, said forward fashion said forward assist adaptor.
assist adaptor further comprising a generally semi-circular 11. The action device as described in claim 10, said forward
cross sectional shape with a plurality of scales along an 25 assist adaptor further comprising a generally semi-circular
extending side in communication with a forward engaging cross sectional shape with a plurality of scales along an
pawl of the forward assist. extending side in communication with a forward engaging
6. An action device for use with an upper receiver of an
pawl of the forward assist.
AR-15 type ?rearm for facilitating use with of a sub caliber 12. The action device as described in claim 6, a barrel
associated with the upper receiver exhibiting an annular
ammunition, comprising: 30
extending neck upon which is exhibited a recessed annular
a generally elongated receiver plate seating a reciprocating
groove, an elongated detent installed within a radially extend
bolt; ing aperture de?ned in said body and accessible with an open
said receiver plate further including a chamber insert lock
mounted forwardly of said reciprocating bolt, said insert interior such that, upon positioning inserting said annular
lock exhibiting a cylindrical shaped main body which is 35 neck within said body, said detent engages within said
both supported upon and situated around a chamber groove.
adapter mounted to a forward end of said receiver plate 13. The action device as described in claim 12, said detent
and proj ecting forwardly from said bolt; further comprising an internally positioned spring which
said upper receiver including a barrel with a con?gured in?uences an end supported ball in engagement with said
inner end within which seats a forward-most portion of 40 barrel groove.
said chamber insert lock upon installation of said action