More 57mm Information
Very interesting chain of information on the 57mm RR rounds. Thought I would add to the data. I have several examples in my collection including the T110 rebatted case experimental, a variation of the T109 already shown, plus a T22 rimmed case variation. In 1943, the 2.36-inch Bazooka was the antitank infantry weapon of choice. It had two disadvantages though, first a low velocity resulting in misses and second, short range effectiveness. So research and development of recoilless rifle systems, including the 57mm were begun at Frankford Arsenal, Pennsylvania. The T110 rebatted rim case was first developed under a program started in August 1946 for an improved lightweight rifle (the T66) and better ammunition. There were two loadings in this case a flat nosed HEAT projectile and a spike-nosed HEAT projectile. The T188E17 and E18 were spike-nosed. My example is the T188E18 fin-stabilized HEAT projectile. The program went all the way to early 1958 when the development of the round was dropped. It is interesting that the date on the T109 is 1957, while the T110 is 1955. Not sure when the T109E2 case John shows was used, but the original T109 case was made in 1957.
Unfortunately, I have very little information on the unique experimental rimmed T22 case version. It was fired from the original Kroeger Musser model of the 57mm recoilless rifle and had an effective range of under 1000 yards. It is lacquered steel case like most of the cases and about 265mm long. Mine is loaded with the M306A1 HE projectile.
There were five common cases used in fielded complete rounds. The M30 had a gilding metal stop ring or gas check at the case shoulder and a brown peper liner inside the case to contain the propellant. The M30A1 used a raised integral case shoulder to act as the stop ring and used a clear flexible plastic case liner. The M30A1B1 used three equall spaced projections on the case as a stop ring and the clear plastic liner. There was also an M30A1B2 and an M30A1B3 both using the raised projections and clear plastic, but with other minor differences.
I also have an M306A1 projectile with the M503A1 point detonating fuze in the standard M30A1B1 lacquered steel case dated 1953. Also an M307A1 HEAT projectile in kronack coated steel case headstamped: 57MM M30A1B1 LOT NOR-3-12-1953. It has the point initiating M90A1 fuze.
The four canister projectiles are experimental designs that led to the fielding of the T25E5 canister round, but they have been placed in mixed cases prior to my receiving them so the case headstamps (many of the 57mm cases did have headstamps) can't be used to date them. The yellow projectile has four longitudinal slits in the body and an "X" slit on the nose to aide in separation. The white bodied projectile has the four side slits, but only a small hole in the nose. The short OD bodied version has the four slits and a solid nose. Finally, the long OD projectile (It is not fully seated, but is still about 10mm longer than the other OD projectile.) has one slit that runs from the top of the gas seal band on one side over to the opposite side.
The subcaliber round was chambered for the cal. .30-06 cartridge also used in the M1 Garrand. The intent was to not develop a unique cartridge for this system. This subcaliber round is designated a "Subcaliber Device" and had no Model number. It was not requisitioned through ammunition channels as an assembled complete round. It was ordered as components and assembled in the field, thus it has no complete round M number. A barrel extension threaded onto the nose of the subcaliber device which then extended down the tube of the recoilless rifle.
The last round is an example of the Communist Chinese copy of the M306A1 HE design, with a 1952 date on it. This round was encountered in Vietnam quite often. The case is unique to the Chinese, with four longitudinal slits down from the case mouth which meant that with rough handling the projectile often came loose from the case. It uses a brass stop ring, a threaded primer and is painted dark green.
I hope that someone gains a little knowledge from this.
