From: Steve Williams <swilliam@oasys.dt.navy.mil>
Subject: Re: 106mm Recoiless Rifle - Rocket or Gun?
Organization: Carderock Division, Naval Surface Warfare Center
Date: Thu, 12 Nov 1992 17:36:22 GMT


From Steve Williams <swilliam@oasys.dt.navy.mil>


In sci.military, gak@n5abi.hou.tx.us (Gene A. Kennedy) writes:

 >hhtra@usho21.hou281.chevron.com (T.M.Haddock) writes:
 >
 >>  Over on the sci.physics newgroup, there was a discussion of
 >>  recoil and the subject of a recoiless rifle came up.  One
 >>  person claimed it was a GUN, another said it was a ROCKET.
 >>
 >>  I also said I thought it was a GUN in that the only difference
 >>  between it and a 105mm howitzer was that the 106's shell casing
 >>  had holes in it which bleed off pressure and propellant which
 >>  escaped rearward through holes in the breech.  But others said
 >>  it was a rocket powered warhead that was ignited and "launched"
 >>  from the tube like a LAAW.  Having fired several of these while
 >>  in the Marines, I don't ever recall the term "rocket" used.
 >>
 > You are basically correct. The shell of the 106 had holes that
 >allowed the gases to escape out the back of the gun. This was
 >designed in such a way as to "balance" the recoil of the firing.
 >In a way though, it does apply the "rocket" principal though.
 >There is consdierable difference between the 105 howitzer round
 >and the 106 so a real comparison there isn't valid either. The
 >recoiless rifle is really neither rocket nor gun in a sense,
 >that's why they came up with "recoiless rifle" :-)
				^^^^^^^^^
Correct spelling is recoilless - there are two l's.

The 106mm ammunition was not a rocket in the sense that it had its own
rocket motor.  It was a projectile with a perforated cartridge case.

The 106mm M40, M40A2 and M40A4 is a recoilless rifle designed for both
anti-tank and anti-personnel roles.  It is air cooled, breech loaded
and fires fixed ammunition.  This rifle is one of the most successful
example of its type.  It came into service in the mid-1950's and is
still used in many parts of the world.

One of the lesser known peculiarities of the 106mm is that it is actually
105mm and is an improved version of the M27 105mm.

The barrel assembly consists of the tube, an enlarged reaction chamber
and a mounting bracket.  The tube is made of alloy steel, screw threaded
at the back to take the reaction chamber.  The breech-block is a short
cylinder with an interrupted screw thread to mate with the segmental
thread in the interior of the recoil chamber.  The breech-block is hinged
on the left side of the breech and is drilled to take the percussion
firing mechanism.

Ammunition for the 106mm rifle is issued in complete, fixed cartridges.
Propellant is contained in a plastic bag within the cartridge case.
The cartridge case is perforated to permit expanding propellant gases
to escape into the enlarged reaction chamber.  The cartridge case has
a well around the primer to permit the breech to be closed.  Proper
headspace is automatically provided for by the seating of the flange
of the cartridge case against the vent bushing.

Depending on the type of projectile, ammunition for the 106mm rifle
is classified as high explosive anti-tank (HEAT), or high explosive
plastic with tracer (HEP-T).  both projectiles are painted olive drab
with yellow markings.  These identifying colors are repeated on the
sealing tape around the fiberboard container.  Both rounds have a 
maximum range of 7700 m.

There is also an anti-personnel round with tracer (APERS-T), which has
a maximum range of 3300 m.


Source: Jane's Infantry Weapons 1990-91


Note: If you saw the movie, Entebbe (a story about the Israeli military 
rescue of the 100+ Israeli hostages at the Entebbe airfield).  You may 
recall the Israeli's using a jeep (or two) with a mounted 106mm.  This
106mm was very effective in destroying enemy jet fighters, strongpoints, 
etc.

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Steve Williams                           swilliam@oasys.dt.navy.mil
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