PRACTICE CARTRIDGE

CARTOUCHE D'EXERCICE

English Abstract

Abstract of the Invention
A practice cartridge is provided for use with a high
powered rifle in place of standard ammunition for the rifle in
order to enable small calibre rim-fire ammunition to be employed.
The device consists of a body having an external configuration
substantially the same as that of a standard cartridge for a
rifle to which the device is to be fitted, which device is formed
internally with a chamber and rifled barrel of dimensions
appropriate to the small calibre ammunition to be employed. The
chamber is recessed to enable a plug to be inserted therein behind
a cartridge, the plug serving to transmit a firing impulse from
the firing pin of the rifle to the rim of the cartridge by means
of a projection formed on the outer periphery of the inner end
of the plug.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A practice cartridge for a rifle comprising a one
piece body of generally similar external dimensions to
a standard cartridge for the rifle with which the practice
cartridge is to be used, the body having an axial internally
rifled bore extending between a muzzle at the front of the
body and an internal chamber which communicates via a
recess with the breech end of the body and is dimensioned
to accept a rim-fire cartridge of substantially smaller
calibre than said standard cartridge, and a removable plug
insertable and sealingly slidable in the recess behind a
small calibre cartridge placed in the chamber, the plug
being formed with at least one projection on the periphery
of its inner end adapted to transmit a firing impluse to
the rim of the cartridge, and with an external peripheral
groove containing an O-ring whereby to form a sliding seal
with the wall of the recess in the body, and the body being
formed with widely spaced external peripheral grooves
containing O-rings adapted to enter gas-tight engagement
with the chamber of a rifle in which the cartridge is loaded.
2. A practice cartridge according to claim 1, wherein the
outer end surface of the plug is formed with an insert of
softer material whereby to prevent damage to a rifle firing
pin striking the plug when the cartridge is fired.

Description

22~7
This invention relates to what may be referred to for con-
venience as a practice cartridge for use with a high powered rifle.
The purpose of such a cartridge is to substitute for the standard
ammunition for the rifle concerned in order to adapt the latter
to fire small calibre rim-fire cartridges such as are readily and
cheaply available in .22 calibreO This enables the rifle to be
used for short range target practice, or for the shooting of small
animals at short range~ which would not be feasible with standard
ammunition due to the excessive penetration and destructive power
of the latter when utilized undçr such circumstancesO Such a
facility has advantages not only in increiasing the versatility
of an otherwise specialized weaponO but also in enabling a large
number of rounds of ammunition to be carried very compactly since
the device of the present invention together with a large number ~`
of small calibre cartridges will weigh and bulk no more than two
or three conventional cartridges for a high powered rifle.
It is known to provide adaptors for shot guns and large
calibre weapons which are in the general form of a cartridge for
the weapon concernedO and which adapt the latter for firing
cartridges of smaller calibreO However~ such devices have not in
general been suitable for use with rim-fire ammunition~ Devices
have been proposed in which rim-fire ammunition is accommodated
,: ., ,
`l by forming the barrel of the device eccentricallyO but such an
, I - .
expedient is unsatisfactory from the point of view of accuracy
and is only feasible when the difference in calibre between the
` weapon adapted and the ammunition employed is very large.
According to the present invention~ a practice cartridge
for a rifle comprises a body of generally similar external con-
: . .
- 1- ~ ,~
, '.

~ 2267
figuration to that of standard ammunition for the rifle with which
the device is to be employedO the body having an internal rifled
bore extending from a chamber which communicates via a recess
with the breech end of the body and is dimensioned to accept a
small calibre rim-fire cartridgeO and a removable plug insertable
and sealingly slidable in the recess behind a small calibre
cartridge placed in the chamber, the plug being formed with at
least one projection on the periphery of its inner end adapted
to transmit a firing impul~e to the rim of the cartridge~
A preferred embodiment of the invention is described with
reference to the accompanying drawingsO wherein:
Figure 1 shows a cartridge in accordance with the invention
disassembled into its main parts,
Figure 2 is a longitudinal section through the same cartridge
when assembledO and
Figures 3 and 4 are inner and outer end views of a plug
portion of the cartridge.
Referring to the drawingsO a practice cartridge comprises
a body 1 whose external configuration resembles that of a round
of rifle ammunitionO except that the portion of the body correspond-
ing to the bullet of a conventional round is tubular rather than
bullet shaped. The exact configuration of the body will of course
depend, like that of conventional cartridges, on the chamber con-
figuration of the rifle with which the cartridge is to be used.
The body 1 should be a snug fit within the chamber of the rifle,
a gas tight relationship and optimum fit being ensured by two
o-rings 2 received in peripheral grooves S formed in the body.
The configuration of the body includes a base rim 6 such as is
- 2 -
'
"': ;
,. ~ . . . ,.. , , -". . , ~ :
'.:: . : '' : .

~ \
1~4Z;2~7
customarily provided on rifle cartridyes to enable their extraction ~;
from the rifle chamber.
InternallyO the body 1 is formed with a rifled bore 7
extending through the body from a chamber 8~ The chamber 8 is
dimensioned so as to receive a small calibre cartridge 4 of the
rim-firP typeO In practiceO this will normally be a ~22 calibre
cartridge because of the cheapness and general availability of
li : ......
this type of ammunition. The bore 7 will of course also be of ; ~ :
a corresponding calibre.
::
The chamber 8 is separated from the breech end of the -
cartridge body 1 by a cylindrical recess 9~ which accommodates a
plug 3 insertable into the recess behind the small calibre cartridge
4. A gas tight seal between the plug 9 and the cartridge body 1
is ensured by an O-ring lOo The inner surface of the plug 3 is
formed with a projection 11 on its periphery~ whilst the outer end
of the plug is provided with a softer insert 12.
; In use~ the cartridge of the invention is loaded by removing
the plug 3~ inserting a suitable small calibre cartridge into the
chamber 8 and replacing the plug 3. The cartridge so prepared
may then be used to load a rifle in the usual way in place of a
' conventional cartridge for the particular rifle concerned.
' IndeedO if the rifle concerned is equipped with a magazine, this
may be loaded with practice cartridges in accordance with the
invention, or even a mixture of such cartridges and conventional
cartridges.
., : . .
When the practice cartridge is loaded into the breech of
the rifle and the latter firedO the firing pin of the rifle strikes
- the plug 3, the projection 11 on which in turn strikes the rim
- 3 -
~'. '~ ..

~L0~ZZ~i7
of the percussion cap of the small calibre cartridge 4, thus
detonating the latter. The bullek from the cartridge passes down
the bore 7 and thence down the bore of the rifle without touching
the latter.
After firingO the practice cartridge is extracted from the
; chamber of the rifle by means of its rim 60 in the same manner
as a conventional cartridge. A small diameter ram rod (not shown)
is passed down the barrel 7 of the practice cartridge to eject
the spent case o~ the cartridge 4 and the plug 3v whereupon the
practice cartridge may be reloaded.
The practice cartridge of the invention enables a high
powered rifle to be utilized to fire small calibre rim-fire
ammunition even though it itself has a centre firing pin. The
insert 12 in the plug 10 avoids any damage to the firing pin of
a rifle which might occur if it struck the unyielding material
of the plug 10, whLcb will be of brass or steel.
,'
~',
" ~
., .
~ '