The Steyr-Mannlicher entrant for the U.S. Advanced Combat
Rifle competition was considered to be an excellent example
of modern technology, but, like the other entries it could not
reach the 100 percent improvement over the M16A2 demanded
by the U.S. Army. The company have said that it represents
their view of the next generation of assault rifles and they
will continue to develop it privately and will probably offer it
for consideration some time early in the next century.
The rifle uses a gas system to actuate the breech mechanism,
which is quite unusual and which is built around the special
cartridge. This cartridge is of plastic, a plain cylinder with the
priming composition arranged in a ring around the inside of the
case, just ahead of the base. A fin-stabilized flechette lies
inside the case, its fins positioned by the primer ring and the
body held by a polycarbonate sabot, and surrounded by propellant.
The breech consists of a block which carries the chamber. At
the commencement of firing an operating arm is held back against
a spring. On pulling the trigger this arm is released to run forward,
take a cartridge from the magazine and load it into the chamber.
The chamber then rises vertically to a position behind the barrel,
where it is locked by a spring catch. Above the chamber is a fixed
firing pin, pointing downwards, and as the chamber rises so this
firing pin passes through a hole in the chamber block and, just as
the chamber aligns with the barrel and locks, strikes the ring
primer and fires the cartridge. The flechette is driven up the
barrel; gas, tapped from the barrel into a surrounding chamber,
drives a piston which is actually a sleeve around the barrel. This
drives the operating arm back, unlocking the chamber and lowering
it to the loading position. As the trigger is pressed for the next
shot, the arm goes forward again, and the cartridge entering the
chamber pushes out the spent plastic case of the previous round,
ejecting it forward of the weapon. There is no rim on the plastic
case, so no obstacle to this forward ejection.
The rifle is a bullpup design, with the magazine almost at the
rear of the stock. The mechanism is enclosed in a plastic outer
casing, there being something of a family resemblance between
this and their well-known AUG rifle. A carrying handle above the
weapon is extended almost to the muzzle, so acting as a sighting
rib for snap shooting, and iron sights are fitted; a telescope can
be quickly attached to the carrying handle. The barrel is rifled
with a twist of one turn in 85 inches, giving roll stabilization to
the flechette to improve accuracy.
The only real defect of the design, as revealed in the U.S. tests,
is that the flechette tends to leave the cartridge at varying
chamber pressures due to inconsistent strength in the plastic
cartridge case. Varying pressures mean varying muzzle velocities
and changes in trajectory from shot to shot, so that accuracy
suffers. This, however, is simply a question of testing various
materials and assembly methods until a consistent release
pressure can be obtained, and it is probable that Steyr has
already solved this, ready to offer the rifle to the next applicant.
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