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 high-intensity 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"
Winchester Magnum and the .338" Lapua. Some rifles go
even further, being chambered for rounds of calibres up to the .50"
Browning heavy machine gun cartridge.
These are described in
THIS article.
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 although this problem is increasingly being
tackled
by fitting a sound
suppressor, the sharp crack of a supersonic bullet still gives clear
warning to the enemy that they are under attack. There has therefore
been a continuing interest in a genuinely silent sniping rifle
for covert operations, 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
(1,050 fps) 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" Auto
from the Colt 1911 pistol
(11.5 x 23 in metric) and fitted with an 210mm barrel and a massive
suppressor. 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 / 14.9 g) round-nosed bullet which lost velocity relatively
quickly 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 (actually 11.6 x 33 B),
which was essentially a shortened .458" Winchester big game round,
firing the usual 500 grain
(32.4 g) bullet at just below the speed of sound. 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.
This prompted the development of cartridges using very heavy, pointed,
boat-tailed bullets of excellent shape to minimise the velocity loss.
Initially
these were modified loadings of existing rifle rounds and such loadings
are
still available in all standard military rifle calibres, as they have
some
utility where the users want to carry only one weapon for both covert
and open
use. However, these are not very efficient: the small calibres limit the
bullet
weight which can be used before the rifling can no longer stabilise the
bullet's
flight, while the cartridges cases are far too big for the small
quantity of
propellant needed to reach subsonic velocity.
As a result, a new breed of specialised
subsonic rounds has arisen in the past few decades. These can only be used in
purpose-designed rifles, usually fitted with short barrels and a large
suppressor. They are designed for maximum efficiency in the role, so have
relative large calibres and use small cartridge cases to fire the heaviest
practicable bullets. The smaller versions are intended for use in suitably
modified military rifles which may also feature selective fire (the capability
for automatic firing), the larger ones for use in bolt-action rifles. Some of
the cartridges are also available with supersonic loadings (for use with or
without the suppressor) so that users can be more effectively equipped for when
covert use is not needed.
One of the first, and certainly the most
prolific, manufacturers of specialist subsonic rounds is SSK Industries
of the USA, who produce the Whisper range of ammunition. These include
6, 6.5, 7, 7.62 (.300 Whisper), and 8.6 mm (.338 Whisper II) rounds, all
using cartridge cases with the same diameter as the 5.56 x 45 but just 35-36 mm
long so they can be loaded with longer bullets while keeping within the same
maximum round length. This enables them to be chambered in rebarrelled versions
of the standard M16 assault rifle, and they can even use the 5.56 mm magazines.
SSK also makes subsonic loadings of the 7.63 x 25 (.30 Mauser) and 7.65 x 21
(.30 Luger) cartridges, marketed as the Mini-Whisper and Micro-Whisper
respectively, with pointed heavy bullets making them too long to be used in the
pistols. Other cartridges are based on the 7.62 x 51 NATO case, but
shortened and again in various calibres: .302, .338 (Whisper I) .375
and .416 Whispers, the last of these (which has so far evaded my collection)
being virtually straight-cased. These can be used in modified 7.62 mm rifles
such as the AR-10 family, or when fitted with shorter bullets to keep the same
overall length as the 5.56 x 45 can be used in an M16 with more extensive
modifications and different magazines. Finally, even larger rounds have been
developed: the .458, .500 and .510 Whispers, based on the .458 Winchester
Magnum, .460 Weatherby Magnum and .338 Lapua Magnum cases respectively.
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