CARTRIDGES FOR SILENCED SNIPING RIFLES

© Anthony G Williams

Amended 10 August 2006

The sniper is the most efficient of soldiers. The current military emphasis on firepower, combined with the use of deterrent suppressive fire, has seen the number of small arms rounds fired per casualty inflicted rise from several hundred at the start of this century to tens if not hundreds of thousands in modern conflicts. Through all this, snipers have maintained a rate of approximately 1.3 rounds per casualty.

The lethal effectiveness of snipers also makes them the most unpopular of soldiers with their adversaries. Detection of a sniper usually results in a mortar attack if not a comprehensive artillery shoot, so snipers have to be experts in concealment as well as crack shots. They also have to be prepared to change position rapidly as soon as they feel that their position might have been spotted.

Most sniping rifles are chambered for the standard military cartridge, currently usually the 7.62 x 51 NATO or 7.62 x 54 R Russian depending on historical allegiance. These are not ideal because a heavier bullet at a higher muzzle velocity would ensure better long-range accuracy, so specialist rifles are available with more powerful cartridges such as the .300" Holland & Holland and the .338" Lapua or BELL. Some rifles go even further, being chambered for the .50" Browning or 12.7mm Russian heavy machine gun cartridges.

All of these rifles have a major disadvantage from the sniper's point of view in that they are very obvious in use. The muzzle report can be heard at great distances and even if this were suppressed to some extent by a silencer, the sharp crack of a supersonic bullet gives clear warning to the enemy that they are under attack. There has therefore been a continuing interest in a genuinely silent sniping rifle, and there is a wider choice now than has ever existed before.

The problem is that a silent rifle has to generate a muzzle velocity below the speed of sound, which is at around 320 m/sec depending on altitude and air temperature. This is in the realm of pistol rather than rifle cartridges so it is no surprise that one of the first and best known of such weapons used such a cartridge. This was the De Lisle Carbine, developed for British special forces in World War 2, which consisted of a Lee Enfield bolt action rifle chambered for the standard .45" ACP from the Colt 1911 pistol (11.5 x 23 in metric) and fitted with an 210mm barrel and a massive silencer. Initial examples used the standard Lee-Enfield stock but a paratroop version with a folding stock was also produced. The problem with the De Lisle was that although it was reportedly accurate to over 300m, the velocity of around 260 m/sec combined with a relatively light (230 grain) round-nosed bullet resulted in a rainbow-shaped trajectory at long range, making accurate range estimation crucial.

The next development along these lines went some way to solving the problem. This was an American bolt action rifle, fitted with a target barrel, a silencer and a telescopic sight, which saw experimental use in Vietnam. It was based around a new cartridge, the .458 x 1.5" Barnes, which was essentially a shortened .458" Winchester big game round, firing the usual 500 grain bullet at just below the speed of sound (the cartridge case actually used by the military was slightly shorter than the 11.6 x 38 B commercial version illustrated, at 33.3mm). It was apparently not entirely successful, largely because the bulk and weight (caused by the long, heavy target barrel) didn't endear it to the troops.

Even this was not the ultimate answer as the bullet was still round-nosed and therefore quickly lost velocity and effectiveness at long range. Enter the current "Whisper" range of cartridges, designed to obtain the best ballistic performance possible within the constraint of subsonic velocity. The first to come to notice was the .30" Whisper (now known as the .300 Whisper), a .221" Remington Fireball cartridge (a short version of the standard 5.56 mm NATO case) necked out to 7.62 mm calibre to take a 210 grain boat-tailed spitzer match bullet. The overall length of this 7.62 x 35 round enabled it to be chambered in a rebarrelled version of the standard M16 assault rifle.

The Whisper range now includes 6.5 mm (6.5 x 35) and 7 mm (7 x 35) rounds also based on the .221" Remington, a 7.63mm Mini-Whisper using the .30 Mauser pistol case (7.63 x 25), a 338" (8.6 x 38) based on the 7mm Remington Bench Rest (which uses a short version of the 7.62mm NATO case), a .458" (11.6 x 45 B) using a shortened .458" Winchester belted case and last but not least a .500" (12.7 x 57 B) using a shortened and necked-out .460" Weatherby case. All of these cartridges are loaded with highly streamlined match-type bullets and it is assumed that they all have muzzle velocities in the region of 320 m/sec, although the Mini-Whisper might be a bit pushed to achieve this.

The Americans are not the only ones interested in this concept as the French have introduced the ANTHIS rifle, based on an ERMA weapon using a STOPSON sound suppressor. The cartridge, based on the .460" Weatherby case, appears to be dimensionally identical to the .50" Whisper and is in fact made in America by A--Square. Any .50" Browning machine gun bullet can be used.

Whether or not all of this activity will result in military use remains to be revealed. The current trend in military operations, towards limited actions with a significant use of special forces, suggest that some at least of the rounds will see action, if they have not already done so.

  Since this article was written, various new developments can be reported.

First, the Whisper range has been extended with the .302 Whisper (7.62 x 38), like the .338 intended for chambering in suitably modified guns designed for the 7.62 x 51, and the .510 Whisper (12.7 x 48) which appears to have replaced the .500.

Second, the Teppo Jutsu range also includes some cartridges type, particularly the .338 Spectre (8.6 x 32) and the .500 Phantom (12.7 x 39 RB).  Read more about the Teppo Jutsu range HERE.

Third, Heckler & Koch have worked with Royal Ordnance to develop a subsonic cartridge of 5.56 mm size for a suppressed rifle, the HK SL9 SD. This 7.62 x 37 is a direct equivalent to the .300 Whisper.

Last but not least, the Russians: they have in service suppressed rifles and SMGs chambered for the 9 x 39 round, which is a necked-up 7.62 x 39 to take a much bigger bullet. They have also introduced the 12.7mm Vychlop, which is similar to the .510 Whisper.

Most of these cartridges are shown below (the 9 x 39 is a dummy - real ones have steel cases). The .500 Phantom and .510 Whisper are both loaded with the Hornady A-MAX, a special long-range bullet also used in the .50 BMG. The Teppo Jutsu and Whisper ranges are also available with lighter bullets loaded to much higher muzzle velocities.

 

CARTRIDGES FOR SILENCED RIFLES
Designation	Case mm	Bullet Weight (grains)	Ballistic Coefficient (estimated)
.45"ACP	11.5 x 23	230	.160
.458x1.5" Barnes	11.6 x 38 B	500	.340
6.5mm Whisper	6.5 x 35	155	.630
7mm Whisper	7 x 35	168	.600
.30 Mini-Whisper	7.62 x 25	165	.500
.300 Whisper	7.62 x 35	210	.630
7.62 mm HK	7.62 x 37	200	.600
.302 Whisper	7.62 x 38	240	.720
.338 Spectre	8.6 x 32	300	.750
.338 Whisper	8.6 x 38	300	.750
9 x 39	9 x 39	250	?
.458 Whisper	11.6 x 45 B	600	.820
.500 Phantom	12.7 x 39 RB	750	1.050 (actual)
.510 Whisper	12.7 x 48	750	1.050 (actual)
.500 Whisper	12.7 x 57 B	650	.710

NB The ballistic coefficient figures are estimates based on modifying the sectional density ratio (a function of the bullet weight and calibre) by a form factor derived from the shape of the bullet. The higher the ballistic coefficient, the better the velocity retention and therefore the greater the effectiveness at long range.

REFERENCES

Military Small Arms of the 20th Century (Hogg & Weeks)
Cartridges of the World (Barnes)
The Cartridge Researcher, January 1997 (item by Barlerin & Regenstreif)

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