SUB-CALIBRE TRAINING DEVICE

"SUB-CALIBRE TRAINING DEVICE"

INTRODUCTION

It is known that for a given weapon system the highest level of training can be achieved by the repeated use of service weapons firing service ammunition in

5. a field environment. Such ideal conditions can rarely be provided, largely due to* the prohibitive costs in¬ volved. The direct cost of the weapon and ammunition can be readily appreciated, but there are also other less visible but very real costs such as those of trans-

10. port to and from a suitable range, of supporting the trainees away from base, the cost of purchasing and maintaining the necessarily very large tract of land, the provision and maintenance of targets and so on.

One possible solution is the provision of a short 15. range version of the original ammunition made by reducing the weight of the shot and the propellant. However for a given calibre of gun this implies a reduction in shot length which introduces problems in exterior ballistics and possibly in feed mechanisms etc. as well as an in- 20. crease in chamber free-volume which is undesirable from a propellant combustion point of view. The cost of such ammunition is generally only a little less than that of the service round, hence it tends to be kept for specialised advanced training exercises.

25. The traditional and more attractive solution to this problem has been the use of sub-calibre ammunition fired either from sub-calibre barrels (either slipped inside or strapped outside the parent weapon) or less frequently from scaled down weapons designed around a

30. cartridge of reduced dimensions. Stricly speaking only the former should be called sub-calibre but time has honoured the title for both systems.

DESIGN PHILOSOPHY

The designer of such training weapons must be recon-

5. ciled to the fact that it will rarely if ever by possible to design a sub-calibre device to simulate the parent weapon in all respects; indeed the art of such design is to identify those aspects which are most relevant and to give them due priority. However the degree of

10. relevance may vary with the circumstances of use which themselves may impose restrictions, e.g. a trainer for use indoors should not generate sufficient noise to force the student and instructors to wear elaborate ear protection which will limit their ability to communi-

15* cate; neither should the resultant smoke be such as to require the use of large^~ extractor fans which them¬ selves tend to be noisy. Ammunition for use outdoors should not only match the trajectory of the service round over the range of interest but should also have

25. a similar time of flight and wind deflection.

Ideally each trainer should be tailor-made to a given weapon and given training philosophy but this approach contravenes one of the basic requirements - that of reducing costs. Compromises must therefore be

30. made which lead to the concept of a family of training devices each of which emphasises a particular range of related aspects of the parent weapon, with mastery of the first device leading logically to the second and so on. Ultimately such an arrangement should turn

25. out the required end product, i.e. proficient weapon operators, and ideally it should do so at reduced cost.

OMPI HISTORY

The first general issue of such devices in-the British Army occurred in 1883 when the "Tube, Aiming, Morris, Martini-Henry Rifle Mark 1" and its complementary

5. "Cartridge, Aiming Tube, Morris" were approved for use. These, the forerunners of a family of Morris Tubes con¬ sisted of a complete chambered barrel of 0.230 inch bore which was slipped inside the service rifle barrel of 0.45 inch bore, held at the muzzle and breech and

10. used the mechanism of the parent weapon to fire the much smaller cartridge. Auxiliary sights were provided to slip over the parent sight to give some harmonisa- tion over a desired range band.

The basic requirement in this case was to allow 15. training with the newly introduced Martini-Henry rifle to be carried out, other than on the few outdoor ranges considered safe for the full bore ammunition. The attend¬ ant advantages were of course a reduction in costs and the chance to accustom the trainees to firing the Mar- 20. tini-Henry rifle without experiencing its notorious recoil. Use of the more common 0.22 inch rimfire ammuni¬ tion would have complicated the mechanisms by requir¬ ing either the bore or the firing pin to have been offset to suit the change from the centre fire to rimfire cart- 25. ridge system.

Following the introduction of the 0.303 inch weapon and ammunition in 1888 the same principle was applied to the "Tube, Aiming, Lee-Metford Magazine Rifle 0.303 inch Morris" which came into service in 1891. Within 30. a few years there was a family of similar devices to suit the range of rifles, carbines and proprietary mach¬ ine guns in service; nine distinct patterns were listed in 1899.

OMPI On the whole this system worked well with -few mech¬ anical problems until the reduction in calibre of the service small arms forced a corresponding reduction in the wall thickness of the tubes making them fragile 5*. and difficult to make.

A sudden massive increase in demand for training devices during World War I virtually sounded the death- knell of such tubes as it was found that less time and effort was involved in making one piece small-bore bar-

10. rels which could be permanently attached to second grade service rifles, with the resultant weapon being designat¬ ed for training use only. Where the weapon was thus permanently modified, it became relatively easy to offset the firing pin and hence to make use of the 0.22 inch

15. rimfire ammunition. This design led to the Rifle No. 2 series of trainers which are still in limited use today.

One disadvantage of this system noted by many users over the years was that the small bore barrel, which 20. contained more metal than its full bore counterpart, made such training weapons heavier overall, with the point of balance being moved perceptibly further from the shoulder.

For the larger naval and coastal defence guns a similar principle was employed using the obsolescent

25. 1 inch Nordenfelt machine gun cartridge redesignated

"Cartridge, Aiming Rifle, 1 inch", which was fired from sub-calibre barrels variously attached in or on the parent barrel, or took the form o"f a replacement breech block containing a firing mechanism and a short length

30. of sub-calibre barrel. Patterns were available for both percussion and electric ignition as required.

-£ J E OMPI RECENT DEVELOPMENTS

Since World War II significant changes have been seen in the requirements for man-portable weapons- which have caused changes in design, often even in the basic

5. principle of operation. Small arms are now at least semi-automatic in operation if not fully automatic and the traditional closed breech gun has been augmented by rockets both in-tube burning and in-flight burning as well as by recoilless guns having the recoil balanced

10. by either gas efflux or by ejected solids. The old prin¬ ciple of providing an expensive but almost everlasting gun from which to fire cheap expendable ammunition has been modified and in some cases even reversed, as now the launcher may well cost less than a single round 15. of its ammunition.

Ideally, training for each of these types of weapons requires a training round operating on the same principle as the corresponding service round. Generally such rounds are available but they are often very expensive, parti- 20. cularly where a one-shot throw-away design has been used for the launcher. Much cheaper rounds should be avail¬ able, at least for initial training.

Designers have approached this problem in a number of ways; the 66 mm HEAT LIA2 system, which consists

25. of an in-tube burning rocket fired from a disposable launcher, has been provided with an ingenious sub-calibre rocket to be fired from a launcher modified to permit a degree of re-use. The 84 mm Carl Gustav recoilless gun has adaptors, each shaped as a round of ammunition,

30. which permit the firing of conventional 6.5 mm or 7.62 mm small arm cartridges. In small arms, the changes have been more in detail than in principle, being mainly concerned with achieving an increase in the rate of fire. Such weapons are some¬ what more complex than their predecessors and hence

5. less amenable to the fitting of simple sub-calibre bar¬ rels. The Australian 7.62 mm SLR is, however, one such rifle which can readily be fitted with a sub-calibre adapter, in itself a complete gun, which, by replacing the original bolt, allows the firing of 0.22 inch rimfire

10. ammunition in a realistic manner. The proposed reduction in calibre for small arms from 7.62 mm to 5.56 mm, i.e. a nominal 0.22 inch, should make the design of such adapters rather more simple although they will no longer be truly sub-calibre. The problem of offsetting the

15. firing pin will still remain and perhaps be aggravated by the smaller volume in which to work.

Sophisticated indoor cine target ranges are now becoming available and have generated a demand for de¬ vices to allow the exercise on them of weapons other

20. than the normal rifle either alone or as part of a team with other similarly adapted weapons. Training may thus be given not only in the weapons themselves but in the elementary tactics involved in the command of a mix of weapons in a range of simulated situations. The low

25. powered 6.5 mm "gallery"' load available for the Carl Gustav is well suited to such applications. No doubt the system could be further modified to fire the more or less standard 0.22 inch rimfire round which would further reduce the costs; however the distinctive 6.5

30. mm hole in the target could be of- some help in assessing the results of fire from a mixed group of weapons.

O PI There are few if any suitable devices for light machine guns presumably due to problems associated with the belting of sub-calibre ammunition and with doubts on the ability of the target mechanism to resolve indi- 5. vidual shots in a burst of fire.

In the Patent Literature reference may be had to prior art as exemplified in United States Letters Patents Nos. 741,079 of 1903, TASKER, 2,541,025, BURFORD et al, 2,857,812, NICHOLS and the specification of Swedish 10. Letters Patent No. 159,014 FRAUSSON.

THE INVENTION

The sub-calibre rocket for the 66 mm Light Anti- Armour Weapon (LAW) , while well suited to outdoor train¬ ing is far too powerful and noisy for use on indoor

15. cine ranges. The present invention, developed by The Weapons Systems Research Laboratory of DSTO comprises a device, which is known for identification purposes as "SCATE" (Sub-Calibre Anti-Armour Training Equipment), which permits the firing of the 0.22 inch rimfire cart-

20. ridge from LAW launchers in a representative manner. This device consists of a sub-calibre single shot gun which fits inside a LAW launcher. The "feel" of the parent weapon is unchanged as the launcher retains its original sights, trigger etc. while the sub-calibre

25. gun closely simulates the weight of the normal rocket. Using a closed breech gun means that the system is not truly recoilless, as is the LAW, however, the use of standard velocity (sub-sonic) cartridges ensures that the recoil sensed by the firer is minimal, while the

30. noise level is sufficiently low to permit continued use indoors. High velocity rounds which closely match the trajectory of the LAW could be used- outdoors with suitable ear protection. An additional safety catch is provided on the gun which is accessible whether ^"in or out of the launcher. For exercising the complete firing cycle of the LAW, the device is loaded and mounted

5. within the launcher which is then closed up, with the sling and end caps fitted in the normal manner. However since the LAW launcher was designed and manufactured as a one-shot disposable unit this process leads to rapid wear of the cocking mechanism as well as inducing

10. damage to the somewhat fragile folding sights.

It is therefore intended that for the majority of training shots, the launcher will be left extended, with the sub-calibre gun being removed for reloading and replaced for firing; recocking of the launcher being 15. done with a special tool. Under these conditions the launcher should remain serviceable for several hundred shots after which the modified components may be switched to another launcher.

The present design is the result of a perceived 20. need to keep this device as simple as possible with minimal operating costs to suit its role as a high usage rate indoor trainer. Variations to the design are pos¬ sible to suit other roles or to emphasise other features of the parent weapon. A two stage version has been demon- 25. strated. It first fires a 7.62 mm blank cartridge, the gas from which is vented in such a way as to simulate the noise on firing of the LAW as well as the motion of the launcher during in-bore travel of the missile and finally to fire a sub-calibre round along the prevail- 30. ing line of- the bore. Tracer rounds of larger calibre could be used for longer ranges outdoors.

OMP The invention comprises a sub-calibre training device comprising in combination:

(a) a launcher for firing a missile such as a rocket along a selected trajectory comprising a barrel having

5. sights and a trigger,

(b) a gun capable of firing a projectile and including a trigger and selected to fit into the barrel of the launcher and having means to support it therein,

(c) means to align the gun with the launcher and to 10. lock it therein, and

(d) coupling means between the trigger of the launcher and the trigger of the gun including a safety lock to prevent accidental firing of the gun.

The means to support the gun in the launcher com- 15. prises a first aligning member forward on the gun engag¬ ing the bore of the barrel of the launcher and a second member at the rear of, the gun rele^'asably engaging the rear of the launcher.

To enable the nature of the invention to be fully 20. understood, an embodiment thereof will now be described with reference to the accompanying drawings which are however merely illustrative and not to be taken as limit¬ ing the invention to the details shown.

DESCRIPTION OF THE DRAWINGS

25. FIG. 1 is a perspective side elevational view of the launcher and the gun with the gun removed from the launcher according to a preferred form of the invention,

FIG. 2 is a somewhat schematic longitudinal section 30. of the rear section of the launcher with the gun in place therein,

OMP FIG. 3 is a rear end elevation of the launcher and gun showing the position of the mechanism when the gun is first inserted into the launcher,

FIG. 4 shows the locking ring turned together with 5. the gun to engage the pins on the launcher in the bayonet slots of the ring, and

FIG. 5 shows the safety catch moved to the disen¬ gaged position to allow the gun to be fired.

DESCRIPTION OF THE PREFERRED EMBODIMENT

10. The launcher can be of usual approved construction as described herein and comprises a barrel 1 having sights 2 and 3 and a trigger 4 and the rear part of this barrel is adapted to have positioned in it by means of a main aligning and locking member 5 the gun 6 which

15. has its rear part locked in position and located by the aligning and locking member 5 which has a ring 7 forming part of it to allow the member 5 to be turned after it is engaged in the rear end of the barrel 1 of the launcher to lock the gun 6 in the barrel 1.

20. The forward end 8 of the gun has a forward aligning member 9 which engages the inside of the barrel 1 and together with the aligning member 5 accurately aligns the gun with the sights 2 and 3.

The trigger 4 is coupled to a pivoted arm 10 on the 25. member 5 and this is disposed to engage a trigger exten¬ sion 11 of the gun. The aligning and locking member 5 also supports a suitable safety catch 12 for the gun, which is so arranged that whether the gun is in posi¬ tion in the barrel or is removed, the gun can be locked 30. against firing.

^0MPI The ring 7 which is part of the aligning and locking member 5 has in it bayonet slots 16 which are adapted to engage pins 17 projecting from the inner wall of the barrel 1 so that when the gun is pushed into position 5. in the barrel as shown in Fig. 3 the gun is automatically aligned by the rear gun aligning and locking member 5 and the front gun aligning member 9 and is locked in position when the ring 7 is turned from the position shown in Fig. 3 to the position shown in Fig. 4.

10. The pins 17 can conveniently be equally spaced around the perimeter of the barrel 1, and the aligning and locking member 5 which includes the ring 7 is cut¬ away at 19 to give access to the gun, the cut-away por¬ tion 19 allowing the pivoted arm 10 to project into the

15. path of the end of the trigger arm 11 so that when the ring 7 is turned from the position shown in Fig. 3 to the position shown in Fig. 4 the end of the trigger arm 11 engages above the end of the pivot arm 10 to allow the trigger 4 on the barrel 1 to actuate the trigger arm 11,

20. the pivoted arm 10 being carried on a pivot pin 20 between guides 21 secured to the barrel 1.

The pivoted arm 10 projects above the pivot pin 20 and engages the end of the rod 22 which connects to the trigger 4 of the barrel 1.

25. The safety catch 12 when in its locked position as shown in Figs. 3 and 4 engages part of the firing mechanism to lock the firing pin against axial movement but when it is desired to fire the gun 6 the safety catch 12 is turned to the position shown in Fig. 5 where it

30. disengages a detent 23 forming part of the safety catch 12 from the firing mechanism of the gun to leave it free to be fired. The detent 23 can engage any appropriate part of the firing mechanism of the gun such as the striker to pre¬ vent the gun from being fired uncil the safety catch 12 is turned to the position shown in Fig. 5 and the detent 23 is withdrawn from engagement with the firing mechanism.

The invention is not limited to use in the existing LAW as with suitable modifications to the mounting and trigger arrangements it could well be made to suit both contemporaries and successors to that weapon.

OMPI