Top
View
NM
groove in the gas cylinder piston
for competition
The
alteration to the pistons adds a .030/.040 wide groove running
along
the piston axis on the large diameter. The groove runs
through
the gas-port hole for the purpose of equalizing the gas
pressure
for a smoother more consistent action. The groove is
ground
to the actual GI national match drawing #9352724. The
original
GI drawing for the standard piston is #7267047 which does
not
specify a polished finish or the groove.
IMPORTANT: THE
NATIONAL MATCH GROOVE IS INTENDED FOR
NM GRADE AMMO ONLY
AND IS NOT RECOMMENDED FOR
SURPLUS BALL AMMO OR
OTHER LOWER POWER AMMO.
If
you plan to shoot NM ammo then the
groove in the piston is
useful.
Otherwise, it was not intended for regular ball ammo (not
enough
power). The groove provides a more consistent pressure
against
the op rod by bleeding off some of the excess pressure
inherent
in high-power Match ammo. This results in a slight recoil
reduction
to help "get back on target" during rapids. It also breaks
the
vacuum between the piston and the cylinder allowing the
shooter
to hear the piston slide down to confirm it isn't fouled.
Our precision pistons are made to
the exact GI
specifications with all critical dimensions individually inspected.
