THE NEXT NATO RIFLE AND MACHINE

GUN CARTRIDGE?

T he conflict in Afghanistan, with its emphasis on tar-geting specific enemy individuals while avoiding col-lateral damage, features the use of weapons of high precision and limited destructive effect. As a result, infantry small arms have a much more prominent

role than that expected in conventional high-intensity warfare and this is highlighting the performance of their ammunition to a greater extent than ever before. Now that several NATO nations have started the process of defining their requirements for the next generation of small arms, this is a rare opportunity to ask the question: Is the present combination of 5.56 and 7.62mm rifle and machine gun cartridges optimal, or could we do better?

LESSONS FROM AFGHANISTAN The British Army has analysed several hundred small-arms

engagements in Afghanistan over the past few years. The results are thought-provoking. Ever since World War 2, around 300 me-tres has been regarded as the normal maximum range for small-arms engagements. However, the Taliban are equipped with PKM light machine guns and SVD rifles chambered in the old but power-ful 7.62x54R Russian cartridge, and more than half of their attacks are launched from ranges of over 300 metres, with almost a quar-ter between 500 and 900 metres. A report on the performance of small arms in the U.S. Army (Increasing small arms lethality in Afghanistan: Taking back the infantry half-kilometer by Major Thomas P. Ehrhart, United States Army) makes similar points. British foot patrols were initially equipped only with 5.56mm guns; the L85A2 rifle, L86A2 Light Support Weapon, and L110A1 Minimi Para light machine gun. However, these weapons have proved inadequate at long range. A combination of battle expe-

by ANTHONY G. WILLIAMS

Peruvian naval infantrymen with F2000 assault rifles conduct a beach assault rehearsal with

U.S. Marines from Special Purpose Marine Air-Ground Task Force 24 and 3rd Assault Amphibian

Battalion on a beach in Salinas, Peru, July 11, 2010. The U.S. Marines were embarked aboard

transport dock ship USS New Orleans (LPD 18) in support of Partnership of the Americas/Southern Exchange, a combined amphibious exercise with

maritime forces from Argentina, Mexico, Peru, Brazil, Uruguay and Colombia. (U.S. Marine Corps

photo by Cpl. Brian J. Slaght/Released)

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rience and the testing of ammunition ter-minal effectiveness has led to a judgment that the rifle (which has a 20 inch barrel) is effective only up to about 300 metres and the light machine gun only 200 metres be-cause of its short barrel of about 14 inches. Similar findings are included in the Eh-rhart report mentioned above. What this means is that more than half the small-arms engagements take place beyond the effective range of a full-length 5.56mm in-fantry rifle, and about 70 percent of the en-gagements are beyond the effective range of short-barrelled carbines like the M4. The second problem with 5.56mm ammunition is its lack of suppressive ef-fect. On most occasions when British foot patrols come under fire, they never see their attackers; the Taliban are skilled at selecting concealed positions for ambush. So the soldiers return fire in the hope of pinning down the enemy long enough for heavier weapons to be brought to bear. Field testing has revealed that 5.56 bul-lets have only half the suppressive radius of 7.62 fire, exacerbated by the fact that the little bullets are more affected by wind drift and therefore less likely to get close to the target. This is supported by battlefield reports that the Taliban basically ignore 5.56 suppressive fire. This lack of effective range and sup-pressive effect are the two major concerns with 5.56mm ammunition reported by the British Army, but there have also been com-plaints about two other issues which have long been highlighted in the USA: erratic terminal effectiveness, even within its ef-fective range, and poor barrier penetration. Erratic terminal effectiveness is mainly due to the fact that the M855 bullet frequently does not yaw and upset rapidly on impact, but may instead pass right through a body point-first, inflicting a relatively minor in-jury unless it happens to strike a vital or-gan. There is anecdotal evidence aplenty of erratic effectiveness in combat, and this has been confirmed by laboratory testing. So have the problems with penetrating intermediate barriers such as walls or car doors and even windscreens. These shortcomings mean that Brit-ish foot patrols now carry 7.62mm weap-ons in place of some of their 5.56mm guns; the very effective L7 GPMG (similar to the

U.S. Army’s M240) and L96 sniper rifles. These weapons are not ideal, as the rifles are bolt action with a low rate of fire and the GPMG is very heavy. This is most un-welcome given that reducing the burden (typically around 100 lbs) worn and borne by the infantryman is one of the top equip-ment priorities of the British Army. The British are following U.S. practice in adopt-ing a semiautomatic 7.62mm sharpshooter rifle (ordered from the American company Law Enforcement International and desig-nated L129A1) and also in seeking lighter 7.62mm machine guns; namely a lightened version of the GPMG and also an even lighter 7.62mm LMG which will match the characteristics of the Russian PKM.

DO WE NEED A NEW CARTRIDGE? Given that we are now adopting a mix

of 5.56mm and 7.62mm weapons at section level, what’s the problem? The 7.62mm guns can deal with the long-range coun-tryside work, with the 5.56 mm retained for urban fighting. One problem with this is that it may not be possible to draw neat lines around scenarios: a section may be clearing houses in a village at one moment then come under long-range fire as they leave. It also means that those carrying 7.62mm weapons will be badly equipped for the close-quarter battle, while those with 5.56mm guns will be unable to partic-ipate in long-range engagements, thereby reducing the effective firepower of the sec-tion in each case. Finally, it still leaves us with the erratic terminal effectiveness and poor barrier penetration of the 5.56mm M855, along with the 7.62mm’s ammuni-

tion weight and recoil. Various attempts have been and continue to be made to uprate the perfor-mance of the 5.56mm cartridge, the most recent being the MK318 Mod 0 which has been adopted by the USMC, and these of-fer some improvements in terminal effects and barrier penetration. However, they involve technologies such as open-point and/or fragmenting bullets, which are re-garded as unacceptable by the British and probably other NATO countries. In any case, the degree of improvement is fun-damentally limited by the small size and modest power of the cartridge. The problem with the 7.62x51, at least in its standard M80 ball loading of 147 grains at 2,700 fps, is that it is effective but not efficient. The bullet does not usually yaw very rapidly on impact; in fact gel tests

indicate that some smaller calibres can inflict more severe wounds. Also, it has an unimpressive long-range performance for its calibre due to the relatively light bullet which sheds velocity quite quickly. The cartridge is effective simply through its raw power and bullet size, but these have a cost in weight (double that of the 5.56mm) and recoil (three to four times the recoil energy compared with 5.56mm rifles of similar weight). The heavy recoil makes training more difficult, slows down double-tap shooting and makes automatic rifle fire virtually uncontrollable. The bal-listic characteristics can be improved by using a heavier and better-designed bullet than the M80, but at the cost of even more ammo weight and recoil, which is definite-ly not what is wanted.

5.56 NATO ROUNDTABLE ANTHONY G. WILLIAMS

ABOVE: A British soldier keeps watch with a 5.56mm L85A2 rifle and 40mm L17A2 (HK AG36) UGL. OPPOSITE: Estonian Army Corporal (CPL) Roman Met-satalu, assigned to the Scouts Battalion, Estonian Defense Forces, Estonian Peacekeeping Center, holds his position armed with a Vektor R6 5.56mm compact assault rifle while awaiting orders to move out on a foot patrol in Western Baghdad, Iraq. Estonian Army Soldiers are working with US Army (USA) Soldiers from 10th Mountain Division, as part of the Multi-National Corps to secure a 15-kilometer section of road in Western Baghdad, during Operation IRAQI FREEDOM.

114 SPRING 2011 SPRING 2011 115

One option is to revert to 7.62x51 completely, but to field a low-recoil load-ing like that used in the Japanese Howa Type 64 automatic rifle, which fires a 138 grain bullet at 2,300 fps (a slight improve-ment on the AKM round). This could be-come the standard rifle round with the option of switching to full-power ammo at long range: the full-power ammo would of course be retained in MGs and DMRs anyway. This solution has its attrac-tions, but the disadvantages would be the need to adjust the rifle’s gas system when switching between ammo types, the need to check each magazine when reloading to ensure that it contains the appropri-ate ammo, and a doubling in rifle ammo weight without doing anything to reduce the weight of MG ammunition. At the moment, neither the U.S. nor British armies seem interested in changing from the current 5.56mm and 7.62mm car-tridges, but are these really the best we can do? The evidence suggests they are not.

THE CHARACTERISTICS OF A GENERAL-PURPOSE CARTRIDGE The most exhaustive recent attempt to improve on the 5.56mm was the de-velopment of the 6.8x43 Remington Special Purpose Cartridge, or SPC. A pri-mary requirement was to keep its overall length within that of the 5.56x45, so that

it could be used in adapted AR-15 guns. To provide the extra propellant capacity required to deliver a worthwhile increase in performance the case had to be wider, and the old .30 Remington case was taken as the basis. Much experimentation with calibres ranging from 5.56mm to 7.62mm followed, and the 6.5mm seemed to be the best compromise until the 6.8mm was tried and proved to be the optimum choice for this case. If what we want is the best available replacement for the 5.56mm at short to medium ranges, then the 6.8mm Rem. fits the bill better than anything else. The author has test-fired the 5.56mm HK 416, HK 416/6.8mm and 7.62mm HK 417 in quick succession, and the 6.8mm gener-ates only a small increase in recoil over the 5.56mm; the gap between the 6.8mm and the 7.62mm is much more noticeable, even with the higher weight of the HK 417. Ba-sically, the 6.8mm is controllable enough for short-range burst fire to be useful, the 7.62mm is not. However, the need to restrict the 6.8mm’s overall cartridge length has re-sulted in a short and relatively light bul-let. The 6.8mm still offers a better long-range performance than the 5.56mm M855, but falls well short of the 7.62mm M80 so could not replace the larger cali-bre. A slightly different choice of case,

calibre and bullet could make a huge dif-ference to the long-range performance while still keeping the ammo weight, energy and recoil in the same ballpark as the 6.8mm. This is clearly demon-strated by the next attempt to produce a better-performing round to fit the AR-15 family, the 6.5x38 Grendel from Alexan-der Arms. This uses a shorter but fatter case to leave enough room for a long, low-drag bullet which loses velocity more slowly than the 7.62mm M80. Both the 6.8mm and 6.5mm are midway between the 5.56mm and 7.62mm in ammo weight and muzzle energy. This graph (opposite page) of bullet energy in foot pounds at different ranges illustrates these points. It compares the 7.62mm M80 (147 grain at 2,700 fps) with the 5.56mm M855 (62 grains at 3,100 fps), the 6.8mm Rem (115 grains at 2,700 fps) and the 6.5mm Grendel (123 grains at 2,600 fps) when fired from 20 inch barrels (results in 14.5 inch barrels follow the same pattern). Two things are obvious: first, that the initial perfor-mance gaps between the 5.56mm and the 6.8mm, and between the 6.8mm and the 7.62mm, become steadily wider with in-creasing range. The second point is that the 6.5mm performs differently; while starting with a muzzle energy similar to the 6.8mm, its more aerodynamic bul-

let allows it to match the 7.62mm at long range. The 6.5mm bullet is also less af-fected by wind drift than the others; a 10 mph cross-wind at 1,000 m deflecting the 7.62mm by 161 inches, the 5.56mm by 230 inches, the 6.8mm by 197 inches and the 6.5mm by 118 inches. These 6.5mm results were obtained with the use of a

specialised target bullet, but a ball round of the same weight and shape shouldn’t be far behind. This indicates the way to obtain a long-range performance to match the 7.62mm M80 with significantly less ammunition weight and recoil: by using a smaller-cali-bre but low-drag bullet fired at a medium

muzzle velocity. The 6.5mm Grendel shows one way to do it, but similar principles could be applied to 6.8mm calibre (perhaps with a 130 grain bullet at around 2,500 fps) or 7mm (140 grains at 2,400 fps). The bigger calibres would hit harder, but weigh more and generate more recoil. Other important points concerning the bullet design of any new cartridge are that it must yaw rapidly and reliably on impact in order to maximise its terminal effectiveness, and also penetrate inter-mediate barriers without being deflected. Armour penetration is of no significance in the current type of conflict, but separate AP ammunition would have to be devel-oped and available in case of need. The above design principles apply to both traditional and advanced ammu-nition types. If an entirely new gun and ammunition system based on the current caseless/plastic-cased LSAT project were to be adopted, it would be a terrible waste of an opportunity if the merits of an in-termediate calibre were not evaluated. It would also be desirable to develop a conventional intermediate cartridge first, both to test the effectiveness of the calibre and to act as a fall-back in case LSAT fails. What might a new conventional car-tridge look like? The designs of both the 6.8mm Remington and 6.5mm Grendel were constrained by the need to be short

5.56 NATO ROUNDTABLE ANTHONY G. WILLIAMS

Republic of Korea marines, armed with K2 rifles, practice pivoting move-ments ahead of a combat marksman-ship program shoot near the Mohican Range, Rodriguez Live Fire Complex, Republic of Korea, Feb. 29, 2008, during Foal Eagle 2008. Foal Eagle is a bilateral training exercise designed to enhance combat readiness and interoperability between U.S. and Re-public of Korea forces. (U.S. Marine Corps photo by Lance Cpl. Gene A. Ainsworth III/Released)

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enough to fit into 5.56mm actions; a new cartridge, for a new family of weapons, should not face this limitation. One final observation: some people ar-gue that the fighting in Afghanistan is not typical, so if we dropped the 5.56mm in favour of a more effective intermedi-ate cartridge we would be equipping for the last war, not the next one. However, current thinking in both the British and U.S. Armies is that asymmetric warfare against insurgent forces will remain the most probable type of conflict in the fu-ture. That means “boots on the ground”, with infantry warfare and weapons re-maining important. The less stable parts of the world, where such conflicts are likely to take place, often have areas with little vegetation and few buildings where there is lots of scope for long-range fire. Besides, what would be the disadvantages of changing calibre even if future com-bat is at shorter ranges? We would still benefit from ammunition that is much more effective than 5.56mm at any range, and lighter than 7.62mm: advantages well worth having in any circumstances. This is especially so considering that full-power 7.62mm rifles and MGs are still in common use in many parts of the world, which puts troops armed with 5.56mm weapons at an increasing disadvantage as the range lengthens. None of this is rocket science. We could have gone down this intermedi-ate calibre path decades ago, first with the U.S. .276 Pedersen in the 1930s then with the British 7x43 in the 1950s, and we should not, yet again, ignore the op-portunity to do so with our next genera-tion of small arms.

ABOUT THE AUTHOR Anthony G Williams is an indepen-dent consultant, co-editor of Jane’s Am-munition Handbook, and co-author with Maxim Popenker of “Assault Rifle: the Development of the Modern Military Rifle and its Ammunition”. He maintains a website at www.quarry.nildram.co.uk.

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5.56 NATO ROUNDTABLE ANTHONY G. WILLIAMS

LEFT: British army Lance Cpl. Mark Cowley, assigned to the 4th Battalion, Yorkshire Regi-ment, holds his L85 rifle during an International Security Assistance Force (ISAF) patrol in Ka-bul, Afghanistan, Nov. 16, 2008. ISAF is assist-ing the Afghan government in extending and exercising authority and influence across the country. (U.S. Air Force photo by Tech. Sgt. Laura K. Smith/Released)