15-069 Garand Picture of The Day

[Mark in Rochester]

So what does this accessory do? Prevent muzzle blast from melting snow on the edge of a foxhole?

Bob

dust signature ?

[Sentryduty]

I would think there isn't a lot of dust around in snowy conditions, but I am guessing it is a gas booster for cold weather firing because of the effect of temperature on the expanding gases of the powder. The gas system may have initially been sensitive enough that cold temperatures would cause reliability issues. Just a guess, but even stable modern powers can exhibit a swing of +/- 150 fps in MV from frozen to warm conditions.