Less-lethal Ammunition


© Anthony G Williams




This is an amended version of an article which first appeared in Jane's Police Products Review, October/November 2007, and includes information from British 37mm Baton Rounds, which appeared in Small Arms Review in August 2008


Less-lethal ammunition, also known as riot control ammunition, is a general title for ammunition of various types which may be used in circumstances of civil disturbance to disperse riots or to incapacitate individual rioters, or in hostage rescue or other police operations. It is designed to minimise the risk of death or serious injuries when used as intended. It is important to stress this latter point, as any of these rounds can inflict severe injuries or result in a fatality if used improperly, which is why weapons and ammunition of this type are now known as "less-lethal" (L-L) rather than "non-lethal". Such weapons should only be used by operators who have been trained in the proper use of the particular weapon and type of ammunition being issued. It is essential to obtain and adhere to the guidance issued by the manufacturer of the weapon or ammunition.

There are many different types of L-L weapons and ammunition in service around the world. Some are L-L versions of ammunition for normally lethal weapons (for example, shotguns and 40 mm grenade launchers), others are weapons specifically designed for the L-L role for which no lethal ammunition is generally available (notably, the 37/38 mm riot control guns).

There are three basic types of disabling mechanism used by L-L ammunition; impact, irritant chemical and intense sound and/or light (the "flash/bang" rounds). In some rounds, effects may be combined. For both impact and irritant types, there is a variety of forms of ammunition for use in different circumstances, and this needs to be borne in mind when acquiring and deploying L-L equipment. The equipment which is best for dispersing a rioting crowd may be very different from that needed to disable a specific individual.

This article will consider the characteristics, pros and cons of the weapons and ammunition available today, and look at trends for the future.


Ammunition types


            There is a close relationship between ammunition types and weapon calibres and types, but it is first helpful to consider some general principles.

Impact ammunition is designed to achieve one of two effects: to disperse rioters by inflicting pain, or to temporarily disable a specific individual, usually to make an arrest. In some (but not all) cases, the same weapons and ammunition may be used for both purposes. Some impact projectiles carry marker dye to aid the subsequent identification of rioters.

To disable a specific individual requires an accurate gun firing a single projectile (generally known as a baton round). The design of this projectile is where the greatest ingenuity is required: it must hit with disabling force out to a specified range (which should be beyond stone-throwing range in a riot situation), but must minimise the risk of death or serious injury if used at a much shorter range. Since all projectiles start slowing down from the instant they leave the muzzle, their impact energy will have dropped significantly by the time they reach the longer ranges. Such ammunition therefore has both a minimum safe range and a maximum effective range, and the problem facing designers is to minimise the former while maximising the latter; in other words, to achieve the widest possible effective zone. This can be tackled in various ways.

As a general principle, a heavy projectile travelling slowly will lose velocity more gradually than a light one launched quickly, so will have a wider effective zone. The disadvantage is that a low velocity means a more curved trajectory, which makes accurate aiming at longer ranges more difficult. Another approach is to adjust the composition of the projectile to meet particular range requirements: different hardnesses of material can be used, ranging from soft foam through various grades of rubber or plastic and ultimately to wooden batons. The most sophisticated projectiles with the widest effective zone have a composite construction, typically consisting of a compressible nose section backed by harder material: however, these can only be used in weapons with rifled barrels, to ensure that they strike point-first (batons fired from smoothbores tend to tumble, especially at longer ranges). Various types of "bean bag" are also available; these are designed to spread on impact, thereby minimising the risk of injury, but are mainly useful at short range.

A wider range of options is available for dispersing rioting crowds, since accuracy is not required. Typically, multiple projectiles will be used, such as rubber shot or several short batons stacked in one round. The size and composition of the projectiles will determine their effective zone, and a variety of options is provided by manufacturers.  Some of the more powerful baton rounds are intended for "skip-firing"; that is firing at the ground so that they bounce into the crowd. The design of multiple projectiles for riot control is problematic unless they are individually large: the higher velocity loss of small projectiles means that to reach out to long range they must be launched at considerable velocity, and that poses a risk of injury at short range, especially if the projectiles are smaller in diameter than a human eye socket. For this reason, most multiple projectiles are intended only for use at shorter ranges, with the task of dispersing rioters at longer ranges being addressed by irritant chemical ammunition.

            What is regarded as an acceptable risk of injury will of course depend upon the circumstances. In dispersing a crowd which is disorderly and perhaps causing only property damage, inflicting serious injury would be regarded as unacceptable. At the other extreme, a very aggressive crowd containing armed individuals posing a threat to life merits more robust treatment, since the only alternative might be to open fire with lethal weapons.

Irritant chemical ammunition contains one of three types of irritant which are usually contained within the medium of a fine powder, although they may also come in liquid form: CS (orthochlorobenzamalonitrile) and CN (chloroacetophenone), both known as "tear gas", and OC (oleoresin capsicum) as used in "pepper spray". A synthetic form of pepper is pelargonyl vanillylamide (also known as Nonivamide) which is generally known as PAVA.

Irritant chemical ammunition is normally for use in crowd control situations since, once released to the air, the spread of the substance cannot be precisely controlled. However, some of the rounds containing these substances are "direct flush", that is the powder is projected directly from the gun and spreads from the muzzle. These are designed for use against individuals at very short range, and when using such ammunition it is clearly advisable for the operator to wear appropriate protection. Others are contained within single or multiple projectiles which release the chemicals on arrival; the multiple types usually have a shorter range but are more difficult for rioters to throw back. In some cases the chemicals are expelled with sufficient force to cause the projectile to skitter randomly over the ground, making it very difficult for rioters to get hold of. There are also more specialised barrier penetration projectiles which are designed to penetrate thin walls, doors or glass before releasing their contents; they are particularly intended for use in hostage situations. Finally, there are some hybrid types intended for use against specific individuals: foam rubber impact projectiles which are impregnated with chemicals for added effect. One issue with these is that impact projectiles are usually designed to be aimed at the lower body for safety reasons, whereas the chemicals are of course more effective if released near the face.

It should be noted that irritant chemical rounds are intended only for policing activities – they may not be legally used on the battlefield as they are covered by international agreements banning chemical weapons.

Flash/bang rounds are primarily useful in hostage rescues, to disorient or stun hostage takers for a few seconds to allow them to be overpowered. They may generated a sound of 140-170 dB and a brilliant flash of light of 3-6 million candelas. Their effectiveness is enhanced when used within buildings. Another type of ammunition found useful in hostage rescue situations is the door-breaching round. This is intended to blow off locks or hinges and is used to effect a sudden entry into a locked room. The projectile is usually a solid slug made of compressed powder which disintegrates on impact to pose the minimum risk to anyone behind the door. However, such rounds can’t be described as less-lethal as they could certainly be lethal if they hit a person rather than a door.

Finally, various attempts have been made to combine the effectiveness of the short-range electrical stunning effect of a Taser with the longer range of a projectile-firing gun. Taser International have themselves developed the wireless XREP (eXtended Range Electronic Projectile) which can be fired from a standard 12-gauge shotgun out to an effective range of 30 m.


Calibres and weapon types


The most common type of purpose-designed L-L weapon is the 37/38 mm riot gun. Various calibre designations are used to describe ammunition which may or may not be interchangeable, so a brief comment on this may be useful. This class of weapon and ammunition was first developed for firing signal cartridges (coloured flares fired up into the sky or to mark targets) and such ammunition is still available, although in military use it has increasingly been replaced by similar rounds for the multipurpose 40 mm grenade launchers. The calibre designations have varied, with 1.5 inch, 37 mm, 38 mm and 38.1 mm all being used. These designations are indicative, for the most part, and in many (but not all) instances the ammunition may be interchangeable: but production standards and tolerances vary, so prospective purchasers should check gun and ammunition compatibility. The guns are almost invariably smoothbores, with the notable exception of the British police’s L104A1 and the British Army's L127A1, different guns but both made by Heckler & Koch, which form part of a gun, sight and ammunition system designed to achieve far greater accuracy than other guns of this type, so that specific individuals may be targeted at some distance.

One exception to the general run of 37/38 mm rounds is the ARWEN 37 mm, which uses a rebated-rim case incompatible with the rimmed cases of the other cartridges. The gun is also unusual in that the original design is a five-shot revolver (since joined in production by the ARWEN ACE single-shot gun) rather than the usual single-shot weapon, and it has a rifled barrel to provide a maximum effective range of up to 100 m (although lower-velocity loadings with a shorter minimum and maximum ranges are also available). Originally developed by Royal Ordnance in the UK (the name is short for Anti-Riot Weapon Enfield) and introduced in 1977, the manufacturing rights were sold to the Police Ordnance Company of Canada in 2001. A compatible range of guns and ammunition is also made by Sage Ordnance of the USA. A wide range of impact, chemical and barricade-penetrating rounds is available from both manufacturers.

Very similar in dimensions to the standard 37/38 mm rimmed ammunition is the military 40 mm grenade round. In fact, one firm (Condor of Brazil) makes multi-calibre cartridges which can be used in 40 mm as well as 37/38 mm guns. The major difference between the 40 mm launchers and most of the 37/38 mm ones is that the nearly all of the 40 mm guns have rifled barrels, providing much greater accuracy and a longer effective range. The exceptions are those such as the Milkor "Yima!" which are intended solely for firing riot control ammunition: the purpose of using smoothbore barrels in this instance being that the military explosive projectiles generally use fuzes which need to be spun by the rifling to be armed, so will not function when fired through a smoothbore. The 40 mm cartridges are considerably more sophisticated than the usual 37/38 mm types, featuring smokeless propellant rather than black powder and with a complex high-low pressure functioning system. All but a few of the 40 mm rounds are for the 40 x 46 LV (low velocity) launchers, although their cartridge cases can be considerably longer than the standard 46 mm as they usually enclose the projectiles. The standard 'long' 40 mm rounds have cases measuring 122 mm – the same as the normal 37/38 mm rounds – but some are 228 mm long and will not fit into all 40 mm launchers. The range of L-L ammunition available for the 40 mm launchers is similar to that for the 37/38 mm guns, with the addition of various military natures. These obviously include high-explosive / fragmentation and armour-piercing types, as well as signal rounds, parachute-borne illuminating flares (visible light or infra-red) and some more exotic offerings such as fuel-air explosives (FAE) and video reconnaissance projectiles containing a small camera (usually parachute borne) which sends images back to a monitor to reveal what is happening behind buildings or other cover.

Military 40 mm launchers are generally designed to be more rugged than police equipment, and come in three main versions; single-shot stand-alone launchers very similar to 37/38 mm riot guns, underbarrel launchers designed to be attached to assault rifles, and six-barrel revolvers. The versatility of the 40 mm launcher has led the Swiss firm Brugger & Thomet to design a single-shot launcher and L-L ammunition combination intended for police as well as military use. Their "Safe Impact Round" makes use of the stability and accuracy provided by the rifled barrel to feature a composite projectile with a soft nose and a stiff base, providing a wide effective zone stated to be from 1 to 50 m and with a claimed 95% torso hit probability at 40 m.

L-L ammunition is even made for the 40 x 53 High Velocity ammunition fired from belt-fed Grenade Machine Guns such as the US Mk 19 and the Heckler & Koch L134A1 GMG recently acquired by the British Army. Rheinmetall Defence makes CS and OC filled chemical rounds with a maximum range of 2,200 m while the US Army has developed the XM1057 which fires multiple rubber balls out to a range of 50+ m. Clearly, HV impact rounds cannot enjoy much of a range advantage over the LV types, partly because the small balls used in this example lose velocity quickly, and partly because high-velocity projectiles would be very hazardous at short range. Despite being only slightly longer, 40 mm HV ammunition is emphatically not compatible with LV launchers; in standard loadings it fires a heavier projectile at three times the muzzle velocity.

Less-lethal loadings for shotguns are also available in a wide range of impact and chemical types, just as for 37/38 mm ammunition. Almost all of them are for 12 gauge shotguns, which have a calibre of about 18 mm. There are two obvious characteristics of such an approach to an L-L capability: the first is that the projectiles are much smaller so irritant rounds will hold less of the chosen chemical, and the second is that this gives users the opportunity to switch between lethal and L-L ammunition as tactical circumstances dictate. This latter point might be considered to offer an advantage in flexibility, or alternatively to pose the unacceptable risk of unintentionally firing lethal rounds. A less obvious aspect is that impact baton rounds have to be fired at a higher velocity to deliver the same energy on target as their bigger equivalents. Furthermore, the small calibre means that this will be concentrated on a smaller area of the body. The risk of causing injury can therefore be greater with small-calibre, high-velocity projectiles if they strike in a vulnerable place.

In addition to the common calibres described above, there is a scatter of exceptions. The French police use the Verney-Carron Flash-Ball, which fires a 44 mm diameter rubber ball from compact single or double-barrelled weapons. China produces a range of 35 mm L-L grenade rounds, while Russia makes L-L loadings of their military 40 mm caseless and 43 mm grenade ammunition, plus a special 23 mm shotgun style L-L weapon. Rubber ball ammunition is also popular in Russia for special self-defence pistols which are designed to be too weak to fire high-pressure lethal ammunition. Typical calibres are 9 mm and 10 mm although one class of compact pistol fires 18 mm projectiles from long cartridge cases which also act as barrels. The weaker end of the range of this ammunition (maximum 50 joules) can be owned by the public, more powerful examples being reserved for police and security use.

Finally, the FN 303 should be mentioned, although it does not fire ammunition in the sense used in this article. It is effectively a large and powerful development of a paintball gun, using compressed air to fire 17 mm calibre fin-stabilised plastic pellets which may contain marker or irritant compositions in addition to their primary impact function. The gun provides a combination of a 50 m effective range, accuracy, negligible recoil and rapid repeat shots (it has a 15-round magazine) which some police forces find very useful. A comparable operating principle is used by the US PepperBall company, which produces gas-powered pistols, carbines and even automatic weapons firing pepper-filled pellets. However, as with all small-calibre impact rounds, there is a higher risk of unintended injury if the gun is improperly used, as was tragically demonstrated in 2004 when a student in Boston, USA, died after being struck in the eye by an FN 303 projectile.




            Certain trends concerning the development of both guns and ammunition can be observed. One is the desire to achieve greater accuracy when firing baton rounds, as shown by the growth in guns with rifled barrels such as most of the 40 mm grenade launchers and the British 37 mm L104A1 and L127A1. In combination with higher production quality standards for guns and ammunition, this can extend the accurate range out to 50 m or more. In conjunction with this, more sophisticated impact projectiles have been developed such as the British 37 mm L60A1 AEP (Attenuated Energy Projectile) which differs from the earlier L21A1, also designed for use with the L104A1, by having a hollow nose cone which is stiff enough to deliver the same impact when hitting a soft target but will collapse to spread the force of impact when hitting a hard object – such as a person's head.

            In contrast with this, another trend is to maximise the volume of fire when distributing irritant chemical munitions into a rioting crowd, by the use of multi-shot launchers such as various five and six barrel revolvers in both 37 mm and 40 mm calibre. For this purpose, accuracy is of no great significance so smoothbore guns are satisfactory. New projectiles are commonly designed in order to minimise the risk that they will be thrown back by rioters.

            A third trend is the increasing use of L-L munitions by armies who find themselves increasingly dealing with peacekeeping operations of the sort usually dealt with by riot police. As most such armies now have grenade launchers (usually of 40 mm calibre) designed to fire explosive projectiles, it is logical for them to acquire L-L munitions for use in these guns.

            Increasingly sophisticated projectiles are being developed for special purposes, particularly in rescuing hostages. These include the door-breaching, barrier penetration and flash/bang rounds.

            Finally, the development of electrical stun cartridges may well revolutionise the options available to police forces as they promise the capability to completely disable a target at a distance, without the considerable and potentially dangerous striking energy which an impact round needs to achieve this.


The British Experience


            At the end of the 1960s the tensions between the Catholic and Protestant communities in the British province of Northern Ireland, which had been simmering for some time, erupted into violence. Among other things, this faced the police and the army with major crowd control problems, particularly since protesting crowds frequently contained (and sometimes still do contain) members who attacked the police with bricks, fire bombs, blast bombs and even firearms. It was important to find ways of combating such attacks without using lethal ammunition, which would cause too many deaths and thus inflame the situation even more. The police and the army therefore adopted various tactics and less-lethal weapons in order to break up violent demonstrations and target specific trouble-makers within them. While CS gas and water cannon have been used against crowds in general (and water cannon still are), the need to target specific individuals within the crowd led to the adoption of 37mm calibre riot control guns firing baton rounds (nowadays known as impact rounds).

            These batons are designed to be fired at the abdomen and legs (the latter particularly at short range), as there is a risk of serious and potentially fatal injury if they hit the chest or, especially, the head. The normal operating range for a baton round is 20-40m, but they may be fired at much shorter ranges in an emergency. Over the period 1970-2005 some 125,000 baton rounds were fired in Northern Ireland. These resulted in 17 deaths, the last being in 1989. This works out at an average of ten rounds per day and one death every two years, or a death rate of 0.0136%.

            Until recently these weapons were not used in other parts of the UK, but in 2001 (in conjunction with the introduction of the L104A1 gun and L21A1 round) it was decided to make them available to police forces outside Northern Ireland. In these areas they have not so far been used in riot situations, but as an alternative to lethal weapons against individuals who are posing a threat to others. Between 2002 and 2004 some 50 baton rounds were fired in England and Wales, in 37 separate incidents. The ranges varied between 1 m and 25 m, and 94% hit their target (compared with 67% for lethal firearms). No deaths or serious injuries resulted.

            The baton rounds have evolved over the last 35 years and the major types used are shown here and described below, together with some other calibres.


37x122R (rubber bullet round), 37x122R (L5A4 plastic baton round), 37x104R (L21A1 plastic baton round), 37x104R (current L60A1 AEP), 37x112RB (37mm Arwen round - now made in Canada and USA), 40x46SR (Rheinmetall sponge baton), 40x46SR (Brugger & Thomet composite baton), 43x30 (Russian VG-93), 44x83R (French Flash-Ball), 56mm projectile (SAE Alsetex)

From left to right, batons: rubber bullet, L5 plastic , L60A1 AEP , ARWEN "tadpole", Brugger & Thomet composite, VG-93 plastic

            "Rubber Bullet"

            This was the original baton round used from the late 1960s until about 1975. It uses the same case as the standard 1.5 inch/38mm flare gun cartridge, but loaded with a long, pointed, rubber baton. The case is 122mm long with a rim diameter of 43mm and an outside body diameter of 39.4mm near the rim, stepping down to 38.6mm at a height of 22mm above the rim. The baton is 149mm long and weighs 174g. The gun was smoothbored.

            L5 Plastic Baton Round

            This plastic baton round, or PBR, was introduced in 1973 and replaced the rubber bullet within two years. It was initially known as the "1.5 inch" round. This used a similar 37x122 cartridge case, except that the outside diameter remains at 39.4mm throughout. The obvious difference is that the baton is flat-nosed and made from polyurethane polymer. The L5 remained in service for a long time and went through several marks, the last being the L5A7. The baton is 98mm long, weighs 131g and is fired at 63 m/s.

            L21A1 Plastic Baton Round

            This PBR was a new departure, introduced in 2001 in conjunction with a new riot control gun, the L104A1 made by Heckler & Koch. This gun has a rifled barrel, which in conjunction with the X1 18E3 optical sight and more consistent ammunition performance provides far greater accuracy (when fired from smoothbores, the earlier rounds tend to tumble in the air). The cartridge case is slightly shorter at 103mm, and the baton has more rounded edges to achieve a longer effective range. However, the Defence Scientific Advisory Council concluded as a result of tests that the L21A1, although delivering similar impact energies to the L5A7, could be slightly more dangerous if it struck the head. The baton weighs 98g and is fired at 72 m/s.

            The kinetic energies delivered by the two rounds at different ranges are as follows:


Range Kinetic energy of L21A1 Kinetic energy of L5A7
2 m 257J 274J
20 m 244J 246J
35 m 230J 216J
50 m 215J 200J

            AEP L60A1 Impact Round

            This was introduced in June 2005 to replace the L21A1. It was developed to reduce the risk of inflicting death or serious injury from a head strike, and achieves this by incorporating a hollow nose. On impact with soft tissue this remains intact, but on striking a hard target like the head or breast-bone, it deforms to reduce the peak impact by between one third and a half. This round is known as the AEP, which stands for Attenuated Energy Projectile. The cartridge case, projectile weight and muzzle velocity remain the same as the L21A1, but the case is painted light grey instead of the black of earlier baton rounds. The AEP is claimed to exceed 95% accuracy against a 400mm x 600mm target at 50m.

            Ammunition manufacturers

            The British government does not release information about the manufacturers of baton rounds, probably because they have always been (and remain) controversial in Northern Ireland, due to the deaths and serious injuries which their use has occasionally caused. However, it is known that substantial orders for baton rounds have been placed in Germany. In the 2004/5 financial year, a German company or companies supplied 34,272 L60A1; 267,276 L21A1; and (surprisingly) 50,000 L5A7 rounds. The cost of the baton rounds is approximately £7 each.

            ARWEN ammunition

            This round is really an "odd one out" as it is incompatible with any other 37mm riot control ammunition, with the exception of a similar range made by Sage Control Ordnance of the USA. It uses a rebated-rim case which is 112mm long. The outside diameter of the case is 39.7mm but the rim measures only 32.2mm. The single projectiles all have a characteristic "tadpole" shape, with the 37mm diameter front section just 50mm long, followed by rear section of similar length which tapers from about 24mm to 20mm. The standard AR-1 baton round projectiles weigh 80g and are fired at 74m/s; they are claimed to have an effective range of 20-100m . Various different loadings are available including a reduced-energy AR-1RE (50 m/s: effective range 1-30m); and a number of combined (chemical + impact) rounds including ones firing four cylindrical sub-projectiles.