Heligun EX17.pdf - Forgotten Weapons

RAMMING
HTC-AD 66-29
Ramming in the Heligun is obtained without moving parts by directing gun
gas pressure on rounds in the feeder. Occasionally, a cartridge case
is misaligned during ramming, causing a gun stoppage. Basic alignment
of the rounds is provided by the positive gear-driven feeder sprockets.
Additional study of allowable ram clearances and tolerances is required to
prevent the occasional stoppage. Currently, one-fifth of the stoppages are
of the ram type. They occur periodically in a particular gun mechanism,
indicating excessive tolerance buildup. Marks on a misrammed round
are shown in Figure A-1.
CHAMBER
The revolver chamber shape had three requirements: it must (1) arrest
the rammed cartridge without allowing debulleting, (2) adequately support
the cartridge during firing, and (3) permit easy extraction of the fired
case. The present chamber meets the first and third requirements very
well, but is marginal in the second. An occasional ruptured cartridge
case indicates need of further testing to establish the optimum chamber
shape. Ruptured cases currently account for 5 percent of the stoppages.
ANTIBOUNCE SPRING
During the ramming cycle, the cartridge is propelled through the anti­
bounce spring (Figure A- 2). When the head of the cartridge clears the
forward end of the spring, the finger-like projections move inward to
prevent the cartridge from bouncing out of the cylinder chamber. Part
breakage and failure of the finger projections to close quickly enough
have caused gun malfunctions. Improved design of the antibounce spring
is indicated, as is a possible change in material. Eight percent of the
stoppages are caused by the antibounce springs.
A-3