U.S. patent number 3,785,293 [Application Number 05/324,910] was granted by the patent office on 1974-01-15 for practice ammunition.
This patent grant is currently assigned to AAI Corporation. Invention is credited to Irwin R. Barr, William O. Davis, Nicholas J. La Costa.
United States Patent |
3,785,293 |
Barr , et al. |
January 15, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
PRACTICE AMMUNITION
Abstract
Practice ammunition including a projectile formed by a thin
walled frangible plastic body casing or shell having a spin-weld
interconnected rear closure element and being filled with a loose
mass of finely divided particulate material of substantially higher
density, and preferably of relatively low animal toxicity. The
plastic body casing or shell is smooth walled and formed without
longitudinal grooving, and if fragmented on exit from a rifled
barrel through the combined lateral forces of set-back and
centrifugal force operating to radially expand the mass of
particulate filler. The particulate material is partially dispersed
by these same forces and further dispersed and retarded by wind
resistance after leaving the barrel so as to fall to the ground
within a relatively short distance from the barrel. A key slot is
formed in a rear closure element for rotational locking during spin
welding assembly of the body casing or shell, and a rearwardly
facing annular obturator encompasses the key slot.
Inventors: |
Barr; Irwin R. (Baltimore,
MD), La Costa; Nicholas J. (Baltimore, MD), Davis;
William O. (Baltimore, MD) |
Assignee: |
AAI Corporation (Cockeysville,
MD)
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Family
ID: |
26800067 |
Appl.
No.: |
05/324,910 |
Filed: |
January 19, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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103079 |
Dec 31, 1970 |
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Current U.S.
Class: |
102/529 |
Current CPC
Class: |
F42B
8/16 (20130101) |
Current International
Class: |
F42B
8/16 (20060101); F42B 8/00 (20060101); F42b
009/20 (); F42b 005/22 () |
Field of
Search: |
;102/41,92.7,38 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Stahl; Robert F.
Attorney, Agent or Firm: Pippin, Jr.; Reginald F.
Parent Case Text
This is a continuation of application Ser. No. 103,079 filed Dec.
31, 1970, now abandoned.
Claims
We claim:
1. Disintegrating practice ammunition, comprising
a projectile having a frangible body shell of moldable and
spin-weldable material,
said body shell forming a tapered nose section and a generally
cylindrical mid and rear section,
said body shell being hollow and forming a cavity for containing a
mass of loose particulate filler material,
a closure element closing the rear of said body shell whereby said
cavity is a closed cavity,
an exterior rifling band on said body shell and protruding radially
beyond the remainder of said generally cylindrical mid and rear
section,
a mass of finely divided particulate relatively high density filler
material container within and generally filling the effective
volume of said cavity,
a circumferential spin weld interconnection formed between and
joining said body shell and said closure element,
said closure element having a key slot formed in its rear surface
for rotational locking to assist in enabling spin-welding assembly
of said body shell and said closure element.
2. Disintegrating practice ammunition according to claim 1,
further comprising an annular rearwardly extending obturator
extension formed at the rear of said body shell and encompassing
said key slot.
3. Disintegrating practice ammunition according to claim 2,
said obturator extension being an integral part of said closure
element and being rearwardly and outwardly tapered.
4. Disintegrating practice ammunition according to claim 3,
said key slot being a laterally extending recess.
5. Disintegrating practice ammunition according to claim 2,
said key slot being a laterally extending recess.
6. Disintegrating practice ammunition according to claim 1,
said closure element closing the rear of said body shell being a
plug having an outer cylindrical diameter corresponding to the
adjoining rear section of said body shell.
7. Disintegrating practice ammunition according to claim 6,
said plug having a reduced diameter shouldered forward end and a
cup-shaped rear end,
said cup-shaped rear end of said plug having a tapered annular wall
forming said obturator extension,
said body shell seating and being secured in peripheral sealing
relation on said shouldered forward end of said plug.
8. Disintegrating practice ammunition according to claim 1,
said mass of particulate material being compactible and said body
shell being radially effectively expandable under set-back forces
to effect a compacted and reduced length volume of said mass during
passage of said projectile along a rifled barrel bore and having a
forward surface lying approximately in the zone of or behind the
effective zone of intersection between the tapered nose section and
said generally cylindrical mid section of said body shell.
9. Disintegrating practice ammunition according to claim 1,
a cartridge case having an ignitable propellant charge therein,
and means releasably securing said projectile at the forward end of
said cartridge case.
10. Disintegrating practice ammunition according to claim 9,
said body shell having an annular groove formed therein rearwardly
of said rifling band,
and said cartridge case being secured to said projectile by an
annular crimp of said case into said groove,
the forward end of said case abutting and being of substantially
the same diameter as said rifling band,
said rifling band being integrally unitary with said body
shell.
11. Disintegrating practice ammunition according to claim 10,
said mass of finely divided particulate filler being of multiple
size predominantly within a relatively narrow range of
approximately 0.012 to 0.033 inch in diameter.
12. Disintegrating practice ammunition, comprising
a projectile having a frangible body shell,
said body shell forming a tapered nose section and a generally
cylindrical mid and rear section,
said body shell being hollow and forming a cavity for containing a
mass of loose particulate filler material,
and means closing the rear of said body shell whereby said cavity
is a closed cavity,
and an exterior rifling band on said body shell and protruding
radially beyond the remainder of said generally cylindrical mid and
rear section,
said cavity being devoid of lateral bracing therewithin,
and a mass of finely divided loose particulate relatively high
density malleable filler material contained within and generally
filling the effective volume of said cavity,
said mass of particulate material being compactible and said body
shell being radially effectively expandable under set-back forces
to effect a compacted and reduced length volume of said mass during
passage of said projectile along a rifled barrel bore and having a
forward surface lying approximately in the zone of or behind the
effective zone of intersection between the tapered nose section and
said generally cylindrical mid section of said body shell.
13. Disintegrating practice ammunition according to claim 12,
said mass of finely divided particulate malleable filler being
minute individually discrete metal shot,
and said body shell being formed of plastic material.
14. Disintegrating practice ammunition according to claim 13,
said metal filler shot being selected from materials which are
generally of low animal toxicity.
15. Disintegrating practice ammunition according to claim 12,
said mass of finely divided particulate malleable filler being of
multiple size discrete metal shot predominantly within an
approximate size range of approximately 3 to 1.
16. Disintegrating practice ammunition according to claim 12,
said mass of finely divided particulate filler being multiple size
predominantly within a range of approximately 0.012 to 0.033 inch
in diameter.
Description
This invention relates to practice ammunition which will enable
practice firing of weapons with close simulation of recoil and
report, and will enable cycling of automatic or semi-automatic
weapons without requirement of more expensive and dangerous
standard ammunition.
It is an object of the invention to provide ammunition which is
easily manufactured by molding and spin welding of the casing
components, and including a projectile arrangement which enables
close simulation of standard projectiles in mass and exterior size
and configuration, and which upon exit from a rifled barrel will
fragment and disperse within a relatively short distance while
providing effectively close simulation of recoil and report as
provided by standard ammunition. It is further a major feature of
this invention to provide a fragmenting and distintegrating
practice round as discussed previously, and which is easily
manufactured.
Still other objects, features and attendant advantages will become
apparent to those skilled in the art from a reading of the
following detailed description of a preferred physical embodiment
constructed in accordance with the invention, taken in conjunction
with the accompanying drawings, wherein:
FIG. 1 is a partial longitudinal section view of a round of
ammunition according to the invention.
FIG. 2 is an enlarged longitudinal section view of the projectile
of FIG. 1, and a portion of the cartridge case, chambered in a
rifled barrel and prior to firing.
FIG. 3 is a schematic longitudinal section view showing the
projectile during its travel along the rifled barrel.
FIG. 4 is a rear end view of the projectile of FIG. 2.
Referring now in detail to the figures in the drawing, a cartridge
11 is provided as shown in FIG. 1 to simulate a standard or other
desired cartridge having an essentially similar external
configuration. Alternatively, of course, other cartridge
configurations may be simulated. In the illustrative embodiment,
the cartridge 11 has a case 31 housing a propellant charge 35, and
a percussion primer, which cartridge case, propellant, and primer
may be of conventional construction and will normally be unmodified
from that of the cartridge case, propellant charge and percussion
primer which is employed in the cartridge being simulated.
In the forward mouth end of the cartridge case 31 there is a
projectile 21, which is the particular illustrative simulated
cartridge is secured by an annular crimp 37 of the case 31 into an
annular crimp groove formed in the periphery of the projectile 21.
Externally the projectile 21 may be and is preferably of generally
the same configuration and size as the projectile of the cartridge
being simulated. However, in some instances it may be necessary,
though not desirable in other respects, to elongate the projectile
to some extent in order to provide the necessary mass for the
projectile such as to sufficiently or more closely simulate the
mass of the projectile being simulated. In many instances this
elongation cannot be tolerated as such will be incompatible with
the dimensional operating requirements of the weapon.
The case 31 will normally be formed of the same material as the
cartridge being simulated, although it will be apparent that
various materials may be employed in accordance with conventional
case construction technology.
The projectile 21 is not only formed to simulate the mass and
configuration of the projectile of the real cartridge being
simulated, but is also constructed to have the capability and
property of fragmenting and generally disintegrating into small
particles upon exit from the bore of a barrel. To this end, the
projectile 21, as illustrated in FIG. 2, is formed by a body shell
23, made of a plastic material such as nylon 6/6, nylon 6/12,
polyethylene or polystyrene, with a wall thickness for the
particular particulate material chosen such as to provide
sufficient ductility of the wall to enable the main cylindrical
wall portion to enlarge under radial stress to the full diameter of
the rifled bore of a barrel 41 in which the cartridge is to be
fired, while being of a thickness for the particular material such
that upon exit from the barrel 41 the projectile 21 will fragment
under the internal stresses effected by setback of a particulate
filler mass 24 within the projectile body shell 23, and the
centrifugal forces of the filler mass resulting from rotation of
the projectile 21 about its longitudinal axis by the action of
rifling 43a of the rifled bore 43. In one illustrative embodiment,
a projectile casing 23 of nylon 6/6 has been employed having a wall
thickness of 0.050 inch throughout its length, with the exception
of a rifling band portion 25, in conjunction with a filler mass 24
of loose lead shot having particulate size diameters lying
predominantly in the range of 0.012 and 0.033 inch. The body shell
23 in this instance had a length of approximately 3 inches, and an
external main body diameter of approximately 0.75 inch, with an
internal cylindrical main body diameter along the mid and rear
sections of the projectile 23 casing of approximately 0.65
inch.
The projectile body shell 23 has formed integral therewith along a
portion of the rear section thereof a rifling band 25 which
protrudes radially along the exterior surface of the body shell 23
by an extent approximately equal to the radial depth of the rifling
43a, the cylindrical external diameter of the smooth wall
mid-section 23b and rear section 23c of the body shell 23 being
approximately equal to the internal land diameter of the rifling
43a, so as to chamber within the barrel smoothly. In the
illustrative embodiment mentioned above, in which the wall
thickness along the major extent of the body shell 23 is 0.050
inch, the wall thickness along the rifling wall band 25 has been
suitably formed as 0.070 inch. In this respect it will be noted
that the internal configuration of the body shell 23 is smooth
walled along its entire extent, and the body seal 23 does not
require or have any pre-formed grooving. This smooth wall ungrooved
construction has been found very satisfactory, and is of value in
ease as well as expense of manufacture. It will also be noted that
there is no cross-bracing in any area within the cavity formed by
the body shell 23, including the longitudinal area of the rifling
band 25, as the invention operates on a principle which enables the
filler mass 24 to itself effect and maintain sufficient engagement
of the rifling band 25 with the rifling 43a to effect the desired
rotational motion of the projectile 21 during passage thereof along
the rifled bore 43 for aiding in subsequent fragmentation and
disintegration of the body shell 23 and filler mass 24.
The filler mass 24 may be loaded during manufacture through the
open rear end of the body shell 23, after which this open rear end
is closed by a rear closure and obturator plug 29 which is secured
thereto. In the preferred construction and mode of assembly, the
closure plug 29 has a reduced diameter shoulder 29b and shoulder
stop 29c which fit in contigous relation with the open mouth rear
end of the body seal 23, and the plug 29 is secured in place by
spin welding, including rapid relative rotation of the plug or cap
29 and the body shell 23. To this end, the plug 29 has a key slot
29s formed in its rear surface, which enables rotational locking of
the plug 29 during this spin welding operation. The spin weld may
be effected along either or both of the shoulder 29b and stop 29c,
and is preferably along both zones in order to provide a desired
degree of strength so as to prevent rupture at this junction during
firing and forward motion of the projectile along the barrel bore
43.
Plug 29 is provided with a tapered wall annular obturator flange
extension 29a which aids in sealing of the propellant gases upon
firing and upon movement of the projectile 21 along the rifled bore
43. While the rifling band 25 may also operate to some degree in
this extent, the tapered wall obturator flange extension 29a is
desirable as an additional precautionary measure of sealing, which
may take any excess radial inward compression strain off the
rifling band zone by the propellant gases during initial passage of
the projectile along the rifled bore 43 immediately after firing
and prior to full lateral support by the set-back and centrifugal
action of the particulate filler mass 24. As noted above, this is
the preferred construction, although in some instances it may be
and has been found feasible to form the projectile 21 without the
obturator flange extension 29a, in which instance the rifling band
25 has been found to provide sufficient sealing action with the
rifled bore 43 to effect a desired forward and rotational motion of
the projectile 21 through the rifled bore 43.
In designing and constructing the projectile 21, the particle
material used as a filler 24 should be selected to closely
proximate the density of the projectile being conventional or other
projectile being simulated, which conventional projectile may be
solid or otherwise formed. For instance, in the illustrative
embodiment the dimensions of which are generally given above, fine
sized lead shot of diameters predominantly with the range of 0.012
- 0.033 inch has been employed to simulate a solid steel alloy
projectile having a density of 0.283 pounds per cubic inch, in
which instance the loose, unpacked lead shot material as contained
within the projectile body shell prior to firing has a density of
approximately 0.25 pounds per cubic inch, which is sufficiently
close in approximation to enable satisfactory simulation firing of
the cartridge 11. In selecting the shot size of the particle
material 24, various factors are considered, including packing
density, maximum range, and toxicity. Shot or particles of varying
sizes within a relatively small range are preferably employed,
rather than a single shot size, inasmuch as such offers a better
packing density than a single shot size, and this is of
considerable importance in enabling the filler mass to provide
sufficiently close density to the mass of the projectile being
simulated.
In many instances, it is also important in selecting the particle
material that a material be selected which has relatively low
animal toxicity. Thus, while lead shot is acceptable in some
instances and is particularly desirable from a density standpoint,
in many instances it will not be acceptable in view of its high
toxicity to animals, considering the propensity of various animals
to ingest particle materials from the ground. Particles within the
general range noted above are generally small enough to provide an
acceptable maximum range, which may be of the order of 150 meters
or so, while being large enough so as to fall to the ground and not
to cause an atmospheric toxicity problem.
As has been noted, the filler mass 24 occupies substantially the
entire effective cavity formed by the body shell 23 and rear
closure plug 29, prior to firing of the cartridge, and as shown
particularly in FIG. 2. Upon firing of the cartridge 11, the
projectile 21 is propelled forwardly through the rifled bore 43,
and the particle mass 24 becomes longitudinally compacted under the
setback forces of firing and concomitant acceleration of the
projectile along the rifle bore 43. This setback compacting of the
particle mass 24 causes the plastic body shell to be laterally
enlarged along its cylindrical mid and rear body sections 23b, 23c
as schematically illustrated in FIG. 3, and the total volume of the
thus compacted particle mass 24 becomes longitudinally
substantially foreshortened, also as generally indicated in this
Figure. In the illustrative embodiment the resulting setback and
centrifugal forces acting on the projectile 21, including the
particle mass 24, result in the particle mass being foreshortened
to an extent where the forward surface thereof is generally in the
zone of or behind the transitional juncture zone between the
tapered forward section 23a of the body shell 23 and the enlarged
cylincrical mid-section 23b of the body shell 23. Thus, design
problems in configuring the wall thickness of the projectile casing
in the tapered forward section 23a of the casing 23 are minimized,
as the lateral expansive forces exerted by the internal stresses on
the particle mass 24 and the centrifugal stresses acting
therethrough on the body shell 23 are primarily effected along the
initial cylindrical smooth walled mid-section 23b and rear section
23c, as well as the rifling band zone 25 of the projectile 21.
Inasmuch as the cylindrical mid-section 23b and rear section 23c
have an external diameter only slightly smaller than the internal
maximum or grooved diameter of the bore 43, it will be apparent
that only a very small extent of stretching of the body shell will
be required to accommodate the compacting of the particle mass 24
during movement of the projectile 41 along the rifled bore 43 upon
firing. However, while this is the preferred design configuration
and construction, it is feasible to employ a particle density such
that the forwardmost foreshortened surface of the particle mass 24
will be forwardly of the initial junction zone between the tapered
forward section 23a and mid-section 23b of the body shell to some
extent, as the material of the body shell 23 may be selected or
conditioned such as to provide a sufficient degree of ductility to
enable the further radially inwardly spaced tapered nose section
adjacent this zone to be radially expanded to the bore diameter by
the lateral forces resultant from particle mass setback and
centrifugal action, without rupture, while still enabling
subsequent rupture thereof upon exit from the barrel as a result of
residual internal stresses acting through the compacted and
spinning particle mass 24. For instance, the plastic material may
be subjected to moisture preconditioning if so desired, as by a
short period of immersion in boiling water, in order to increase
its ductility to a desired degree. However, as a preferred
construction, it is desirable that the fragmentation of the
projectile body casing 23 be into relatively small particles after
exit from the barrel, and, accordingly, it is normally most
desirable to employ projectile material of relatively low moisture
content, and thereby render the projectile body more brittle than
would otherwise be the case with a relatively higher moisture
content.
During forward motion of the projectile 21 along the rifled bore
43, it will be noted as shown in FIG. 3 that the compacting and
centrifugal forces acting on and through the particulate mass 24
cause the expanded body case 23, including mid-section 23b, rifling
band 25 and rear section 23c, to be seated into the zone between
and around the rifling 43a, and it has forward motion of the
projectile will effect a helical scoring of the body casing 23,
which aids in the fragmentation of the body casing upon exit from
the bore 43. However, it is of importance that the radial depth of
the rifling 43a be such that it does not cut entirely through the
laterally expanded body case 23 during this motion of the
projectile along the bore 43. In the illustrative example noted
above in which a body casing 23 of a 0.050 inch wall thickness was
employed, rifling of approximately 0.020 inch depth from land to
groove has been found quite satisfactory, this being provided in a
rifled barrel of approximately 20mm internal diameter.
Upon exit of the projectile 21 from the barrel, the residual
internal stresses cause the plastic body case 23 to rupture and
fragment, aided by the helical external grooving effected by the
passage of the projectile along the rifled bore 43. The increased
air resistance on the fragmented plastic parts on the body shell
cause these fragmented parts to slow down and fall to the ground
within a relatively short distance. Once the plastic body shell has
fragmented, the compacted particulate mass 24 is dispersed in a
cone around the exit of flight of the projectile under the
influence of the centrifugal forces acting thereon. Thus,
individual particles are subjected to increased air drag and are
slowed down to an extent that they fall to the ground within a
relatively short distance, as for instance less than 150 meters
from the barrel. Inasmuch as the mass of the disintegrating
projectile 21 may be made to be generally the same as or closely
comparable to that of the projectile it is simulating, the interior
ballistics of the simulated round are comparable to that of the
round being simulated, and thus the recoil imparted to the gun
mechanism is either the same or sufficiently comparable to be
satisfactory, and the report and flash are likewise satisfactorily
comparable.
While it is in all respects preferred that the round be fired in a
rifled barrel as illustrated, it is possible to fire the round,
with or without band 25, in a smooth bore barrel. In the instance
of a smooth bore fired projectile, the break-up of the projectile
will be accomplished solely by the setback forces which effect
corresponding lateral rupture forces on the projectile case as it
emerges from the barrel, as distinguished from both setback derived
lateral forces and centrifugal forces in the case of projectiles
fired through a rifled barrel as in the illustrated mode of
practice. However, in utilizing this alternative firing mode, it
will normally be found that the projectile will rupture and
fragment with a fair degree of dissemination of the particulate
material. Nevertheless, the major body of the particulate material
appears to remain within a generally substantially smaller cone
dispersal pattern. For instance, with the rifled barrel mode of
practice of the invention, the particulate material is found to be
acceptably dispersed and distributed within a cone angle of
approximately 15.degree. to 20.degree., using a conventional 7
degree rifling in a 20 mm barrel bore, and this has been found to
yield a cone dispersion of 5 feet radius at a 50 foot range,
whereas with a non-rifled smooth bore barrel employing the same
projectile, with or without a rifling band, the pattern is
substantially much more concentrated within a smaller cone angle,
and with the greater volume of particulate material within an even
smaller cone angle in this instance.
As has been noted, the loose filler mass initially effectively
filling the cavity formed within the body casing 23 may be formed
of various materials, one illustrative embodiment of which is lead
shot. Alternatively and in many instances more preferable from the
standpoint of animal toxicity, although in some instances
substantially less preferable from the standpoint of density
requirements, one may employ iron or steel particles, also
preferably in the form of multiple sized shot which may be of
approximately the same size as that mentioned above in the case of
lead shot. Also, various other materials may be employed in a given
instance where the conditions merit, including tugsten, copper,
brass, etc.
While the invention has been described with respect to a single
preferred embodiment, it will be apparent that various
modifications and improvements may be made within the scope and
spirit of the invention. Accordingly, the invention is not to be
limited by the particular illustrative embodiment, but only by the
scope of the appended claims.
* * * * *