Barrel inserts help cut costs: an increasing number of countries have to face the severe problems posed by space limitations for training exercises.
It so happens that barrel insert systems (Bis) and subcalibre devices can both overcome the more severe of firing range limitations and achieve cost savings in terms of ammunition. Moreover, the use of such subcalibre training devices will also reduce the wear and tear on gun barrels, thus providing added savings; Reflecting the special nature of this aspect of training, suppliers of subcalibre devices and the appropriate ammunition often work together with different gun or training equipment manufacturers.
Thus, Dynamit Nobel, Krauss-Maffei Wegmann (KMW), Mauser-Werke and Oerlikon Contraves have a record of being closely associated with training or artillery system prime contractors. As Alpine countries such as Austria and Switzerland are particularly hard-pressed to find space in which to fire guns to their maximum range, barrel insert systems offer an acceptable solution.
Therefore, faced with the need to train tank crews in handling 105 mm and 120 mm guns, Ruag Land Systems teamed with Mauser-Werke and Oerlikon Contraves Pyrotec to develop the Sub Calibre Offers Realistic Exercises (Score) system. Since adopted by the armies of Switzerland and Austria, the Score makes use of a 27 mm barrel insert system, which has proved to bring about significant savings in ammunition and other costs. As most of the deep valleys in both countries are put to more productive use than firing ranges, the problem of space limitation has also been largely overcome.
A tank crew familiar with Score can install it in a matter of ten minutes without the need to modify the tank, which can then be used to conduct realistic training for the entire crew--not just the gunner. In practice, it has been shown that training goals such as fast target acquisition and a high first hit probability can be achieved up to full combat distances.
The environmental and safety aspects of the Score system are particularly important for forces that must be alert to criticism from those living close to the boundaries of exercise grounds. Clearly 27 mm rounds have less potential for damage than full-calibre ammunition, so as far as the Swiss Army is concerned, the Score has established a place for itself in a four-part training plan.
Under this plan, tank crews begin their training on an indoor simulator before graduating to a real main battle tank fitted with a laser training system of the kind produced by Saab Training Systems and Cubic Defense Systems. The Score then provides the crew with an opportunity to fire real ammunition out to ranges of 1800 metres, after which, having become familiar with the aiming and fire control equipment for the main gun, full calibre ammunition can be used.
However, given that the 27 mm Target Practice Frangible Projectile with Tracer (TPFP-T) produced by Oerlikon Contraves for the Score system costs 4.2 per cent of a full-calibre round, dramatic costs savings have been achieved. If 80 per cent of ammunition fired each year is comprised of TPFP-T training rounds, with the balance made up of full-calibre rounds, then total annual costs would be little more than 20 per cent of using only the latter.
But while some savings are made in terms of reduced barrel wear, other advantages provided by projectile fragmentation on ground impact include, no duds (because the TPFP-T has no explosive or fuze), no ricochets, no destruction of targets (except perhaps a 27 mm hole) and a considerable reduction in the size of the safety area. In all probability, small ranges are closer to barracks and their tanks, and this will result in reduced wear and tear in terms of engine and other automotive components.
The 27 mm barrel insert of the Score system is a development of the 35 mm system produced by Mauser and the former Wegmann, now absorbed into KMW. The components comprise the insert barrel with smoke evacuator and coupling, a sound absorber, the barrel fixing element, ammunition storage and a breech opening unit, for use with the Swiss Pz 87 and other Leopard II tanks.
Other 105 mm and 120 mm tank gun users may prefer to use the KMW 35 mm Barrel Insert System that has all the benefits of the lower-calibre Score system but has external ballistics up to 2000 metres. However, whereas ammunition in the 27 mm system is loaded directly into the barrel, adaptation cartridges are used with the 35 mm insert.
Israel Military Industries (IMI) has developed a number of training systems for tanks fitted with guns of 100 mm, 105 mm or 120 mm calibre. For the last two, a 20 mm Inbore Subcalibre Training Device (ISTD) has been designed for use with guns with an electrical firing mechanism, and can be quickly inserted into the barrel of the tank's gun. The system can also be used with a 76 mm tank gun to fire 20 mm rounds through the barrel while making use of a shell casing shaped like the standard tank round, which also replicates its size and weight.
The ISTD produced by IMI can be deployed against static or moving targets, obliging the gunner, loader and commander to perform aiming and firing tasks realistically. Rounds fired by the system generate a visible impact on targets out to 2000-metre ranges by day and night. For training crews of tanks fitted with a 100 mm gun, IMI's 23 mm training device uses 23 x 152 mm rounds with a percussion primer. All the IMI systems can be easily installed by tank crews and are compatible with standard fire control systems.
Similar claims are made for the devices offered by Cockerill to support users of its 90 mm guns. Clearly the subcalibre concept is not limited to main battle tank guns. Indeed, the light armoured vehicles on which the company's 90 mm guns are mounted can be fitted with one of two subcalibre devices.
Both are intended for use with Cockerill 90 mm Mk III or Mk IV guns and promoted as a low-cost aid to instruction and practice in firing, ranging and laying methods but differ mainly in the calibre of the training ammunition used. The Dynamit Nobel subcalibre gun for example, uses 14.5 mm rounds and has a range of only 100 metres. This short range emphasises that the Dynamit Nobel device is intended for initial gunnery training in which all of the appropriate actions in firing full-sized ammunition are practised.
Thus, aiming, firing techniques, zeroing, direct firing against static or moving targets, as well as semi-direct and night firing can be practised whilst employing the fire control system of the main weapon. The muzzle velocity of the 14.5 mm gun is only 150 m/sec, so the recoil force is negligible and some may criticise a system that does not fully replicate the conditions experienced when firing the main gun. But the advantages of cost savings that apply to the main battle tank barrel insert systems apply equally well to vehicles fitted with guns of smaller calibre.
So light armoured vehicles fitted with the lighter of the Cockerill subcalibre devices will be able to use reduced scale firing ranges, while benefiting from savings in ammunition and mechanical wear costs. However, by using the 20 mm subcalibre device produced by Oerlikon, crews can be given more realistic practice in firing live 90 mm ammunition.
With a muzzle velocity varying between 1100 and 1200 m/sec depending upon the type of ammunition used, the Oerlikon subcalibre device provides the advantages of the lighter calibre system but with a firing range of 800 to 1000 metres. The 20 mm system ensures a better ballistic simulation of the main gun so that firing training and gun handling are closer to reality. Users of the Cockerill 90 mm gun may well find that both the 14.5 mm and 20 mm devices have a place in training programmes.
Mention of the Cockerill 90 mm provides an almost natural link with American Apex which is currently in the process of having a version of its Aimtest system type-approved for that barrel at the Aberdeen test centre following a very keen interest voiced by Saudi Arabia. American Apex produces the Aimtest insert for 105 and 120 mm guns and has supplied well over 350 units to the US Army and the National Guard over the past seven years, but it appears that a large bulk order could materialise for the US armed forces in the forthcoming months. The American Apex system now incorporates a new patented Anti-rotation Counter-Recoil Assist device, dubbed Arcra, which prevents the insert from rotating under firing torque effect. The Aimtest seems to have scored rather nicely on the international market as well, adopted as it has been by Egypt, Spain, Greece, Bahrain and Brazil to name but a few, and it could eventually reach Jordan for use in that nation's Challengers (see our tank upgrade feature article in this issue).
Dynamit Nobel has also produced 14.5 mm subcalibre artillery trainers that have been supplied to more than 20 countries to provide indirect fire instruction. In its most basic form, this system is simply tripod-mounted so that the gunner may practice use of the dial sight system of the real gun.
However, a subcalibre version of the system can also be inserted into the barrel or breech of various guns and howitzers for which adapters have been produced. The, maximum range of the artillery trainer is 1150 metres, so space limitations can be easily accommodated while ammunition costs are reduced.
Using a launch pod/container identical to that of the standard MLRS, Dynamit Nobel has developed a 110 mm subcalibre training system for multiple-launch rocket systems. While using light artillery rockets in service with the German Army, the training system has a range of up to 14 km compared to the 40 km or so achieved by the full-sized MLRS. Apart from adapting the fire control system to light artillery rocket ballistics, only minor modifications to the MLRS are required.
Dynamit Nobel has also produced subcalibre indirect fire training systems for mortar users. Compatible with 60 mm, 81 mm, 120 mm and 4.2-inch mortars, this system is in service with a number of forces including Nato armies. Operators make use of special range tables and the system consists of a full-sized training round, 25 mm blank ammunition and a sub-projectile of similar calibre, which produces a satisfying bang and smoke.
On being loaded in the normal way, the 25 mm blank cartridge is fired, propelling the subcalibre projectile to maximum range of 520 metres (depending upon the type of blank cartridge use), while the training round is ejected to a range of only a few metres. It can then be recovered for reuse with another blank cartridge and sub-projectile.
In service with more than a dozen armies, a subcalibre mortar training system has been produced by Nico-Pyrotechnik. Like the Score subcalibre system, use of this mortar system is claimed to cost only some 20 per cent of full-sized rounds. The Nico-Pyrotechnik system makes use of full-sized dummy mortar rounds, which incorporate a 22 mm subcalibre cartridge. Used to replicate most standard calibres, this training system can cover a variety of ranges achieved by the use of four different charges out to a maximum of some 430 metres.
Although Canada has space to spare for training, a need to make best use of limited ranges has nevertheless led SNC TEC to develop a 105 mm subcalibre round for L7 and M68 tank guns. Known as the C148, this employs a discarding sabot base and the training round launches a projectile matching that of the APFSDS out to 2500 metres but then becomes unstable, so that the maximum range is reduced to some 7.5 km. It incorporates a tracer that ensures good visibility up to 2500 metres and its use has proved to make for low barrel wear and lost cost compared to operational rounds.
Another example of SNC TEC's innovation in training resulted from collaboration with the IMT Corporation in the development of Target Radar Augmented Projectiles (Trap) for naval use. Produced in a wide range of calibres, the Trap is a low-cost, low radar cross section supersonic/transonic target that is capable of emulating different types of anti-ship missiles.
The Trap can be launched from standard, unmodified naval guns and howitzers to become an expandable radar target that is used by a number of navies in North America and Europe. The system is used to evaluate and maintain the performance of above-water air defence equipment and personnel.
Returning to land warfare training, the DM4P is a 120 mm practice round for tank guns developed by Rheinmetall, which was later developed by Alliant Techsystems as the M865 training round for use with the M1A1 Abrams. This features a high-drag tail, which begins to take effect at some 2000 metres after firing and reduces the maximum range to around 7.5 km instead of the 30 km-plus achieved by the standard round. The DM4P and its derivatives are in service with the US Army and Marine Corps, as well as the German Army.
While training rounds and subcalibre systems are mostly devoted to artillery needs, Armalite has developed a subcalibre training system for the Mk 19 automatic grenade launcher. Dubbed the AR-22, this training device makes use of standard 7.62 mm blanks that are inserted into a special 40 mm grenade case. In common with other objectives for larger-calibre training devices, the AR-22 aims to meet a perceived requirement to train infantrymen in firing the Mk 19 without the need for a large firing range. The new device simulates the firing effect of the 40 mm grenade while cutting down on ammunition costs.