Recoilless Rifles
A recoilless gun or recoilless rifle (RCL) is a lightweight form of weapon that allows the firing of a heavier projectiles than would be practical with a recoiling weapon. Technically, only devices that use a rifled barrel are recoilless rifles, smoothbore variants are recoilless guns; this distinction is often lost, and all are called recoilless guns.
Recoilless Rifle Information
Roles
Normally used for anti-tank roles, the first effective system of
this kind was developed during World War II. Recoilless rifles are
capable of firing artillery-type shells at a range and velocity
comparable to that of a normal light cannon, although they are
typically used to fire larger shells at lower velocities and ranges.
The near complete lack of recoil allows some versions to be
shoulder-fired, but the majority are mounted on light tripods, and
are easily carried by a man.
The typical recoilless gun functions very much like a conventional
gun. The projectile and propellant are supplied as a single round
and loaded into the breech. When fired, however, instead of all the
propellant blast following the projectile out the barrel, a large
portion is allowed to escape to the rear, providing an inertial
force to counter the inertia of the projectile. Since recoil has
been mostly removed, the heavy and complex gun carriage and recoil
damping mechanism can be dispensed with. Despite the name, it is
rare for the momentum to completely balance, and real world
recoilless rifles do recoil noticeably.
Unlike a rocket launcher, which fires fin-stabilized rockets from a
smooth bore, recoilless rifle rounds resemble conventional artillery
shells. They generally have a rifling band to engage the rifled
launch tube, spin-stabilizing the projectile, hence the term
"rifle". The "case" area of the shell can be perforated to vent the
propellant gases which are then directed to the rear, as the base of
the shell disintegrates.
The Armbrust recoilless gun, and its successor the MATADOR, uses a
unique design that combines a rocket-like projectile (finned to
allow a smoothbore barrel) with a recoilless gun firing mechanism.
The fin stabilized Armbrust projectile is packaged in a "cartridge"
containing the propellant charge and a countermass of shredded
plastic. Upon firing, the projectile is propelled forewards and the
countermasss is propelled backwards. Unlike conventional recoilless
rifles, where the countermass is hot gas, dangerous in a confined
space, the Arbrust's shredded plastic countermass is harmless at a
distance more than a few feet from the breech, allowing firing in
enclosed spaces.
History
The first recoilless gun was developed by Commander Cleland Davis of
the US Navy, just prior to the First World War. His design connected
two guns back to back, with the backwards-facing gun loaded with
lead balls and grease of the same weight as the shell in the other
gun. His idea was used experimentally by the British as an
anti-Zeppelin and anti-submarine weapon mounted on an O/100 bomber
aircraft. During the Second World War the Swedish company Carl
Gustav developed a small 20 mm device, the 20 mm m/42; the British
expressed their interest in it, but by that point anti-tank rifles
were already out of date.
In the Soviet Union development of recoilless weapons ("Dinamo-Reaktivnaya
Pushka" (DRP), roughly "dynamic reaction cannon") began in 1923. In
the 1930s many different types of weapons were built and tested with
calibers ranging from 37 mm to 305 mm. Some of the smaller examples
were tested in aircraft and through some limited production and
service, but development was abandoned around 1938, possibly as a
side effect of Great Purge. The best-known of these early recoilless
rifles was the Model 1935 76 mm DRP designed by L.V. Kurchevski. A
small number of these mounted on trucks saw combat in the Winter
War. Two were captured by the Finns and tested; one example was
given to the Germans in 1940.
The first recoilless rifle to enter service in Germany was the 7,5
cm Leichtgeschütz 40 ("light gun" '40), a 75 mm gun developed to
give German airborne troops some useful anti-tank support before the
Panzerfaust, itself a simple unrifled recoilless gun, became
widespread. The 75 was found to be so useful during the invasion of
Crete that a larger 105 mm version was developed on the same basic
pattern. Interestingly both of these weapons were loosely copied by
the US Army, reversing the flow of technology that had occurred when
the Germans copied the Bazooka. The US did have a development
program and it is not clear to what extent the design was copied, as
there were in fact differences. The Japanese had also developed a
portable recoilless anti-tank rifle which they had reserved for the
defense of anticipated invasion of the mainland. As it was, however,
PAWs remained fairly rare during the war though the US versions of
the 75 started becoming increasingly common in 1945.
By the time of the Korean War recoilless rifles were found
throughout the US forces. The original 75 mm and 106 mm versions had
also been joined by new 57 mm and 90 mm versions. The "original" US
recoilless rifles were the 57 mm and 75 mm followed by a 105 mm. The
new models replacing these were the 90 mm and 106 mm. The Soviets
likewise enthusiastically adopted recoilless rifle (actually
recoilless "guns" as they were smoothbore) technology in the 1950s,
most commonly in calibers 73 mm, 82 mm, and 110 mm (107 mm, not 110
mm).
The British, whose efforts were led by Denis Burney, inventor of the
Wallbuster HESH round, were developing recoilless designs. Burney
demonstrated the technique with a recoilless 4 gauge shotgun. His
"Burney Gun" was developed to fire the Wallbuster shell against the
Atlantic Wall defences but was not required. He went on to produce
many designs including a man-portable 3.45" (88 mm) recoilless
rifle, the Ordnance, RCL, 3.45 in pushed into experimental service
in late 1945. Post-war work developed and deployed the BAT series of
recoilless rifles culminating in the 120 mm L6 Wombat (Weapon of
Magnesium, Battalion Anti-tank).
Lightweight SPG-9 73 mm and B10 82 mm heavy recoilless rifles are
still in service in the Russian army in airborne units, and are
found quite commonly around the world in the inventories of former
Soviet client states, where it is usually used as an antitank guns.
As the wire-guided missile became more and more popular in the late
1960s and early 1970s, the recoilless rifle started to disappear
from the military. The last major use was the Ontos tank, which
mounted six of the US 106 mm on a light (9 ton) tracked chassis
first developed for use by the US Army airborne troops in 1950.
However the Army considered them useless, and the Marines picked
them up instead, albeit only 176 of them. They used them to great
effect as a fire support vehicle during the Vietnam War. The crews
continued to report the Ontos was a very effective fighting vehicle
in this role, but the military brass continued to argue for heavier
designs, and in 1970 the Ontos was removed from service and most
were broken up.
Today the only remaining front-line recoilless rifle in the armies
of most industrialized Western nations is the famous Carl Gustav
recoilless rifle, an 84 mm man-portable anti-tank weapon. Similar in
conception and use to the Bazooka, the weapon differs primarily in
using rifling for stabilization rather than fins, and does not
include the complex breech that is the mark of most RCL designs.
First introduced in 1946, it is still in widespread use throughout
the world today, and has even been re-introduced into the US Marine
Corps as an anti-bunker weapon. M40 recoilless rifle 106 mm
recoilless rifles of US manufacture, mounted on jeeps or similar
small vehicles, are very common in the armies of many poorer
countries, where they serve in the role of tank destroyers.
Perhaps the oddest adaptation of a recoilless rocket was the M-388
Davy Crockett, which used a recoilless rifle to launch a tactical
nuclear warhead, deployed by the United States in the 1960's.
Older discarded 75 mm weapons are still used by the U.S. National
Park Service as a system for avalanche control, an interesting case
of swords to ploughshares.