Thread: 'Subsonic' .22 ammo going off with a crack

Originally Posted by Bagheera

Apparently the speed of sound depends mostly on temperature and not much on pressure or altitude.
https://en.m.wikipedia.org/wiki/Speed_of_sound

At 20C it is 1125 f/s
At 0C it is 1086 f/s and “Standard Velocity” ammo might creep over that.
I understand there are special low temperature ammo for biathlon to avoid the bullet going across the speed of sound and becoming unstable.
I wonder if this happens more in the autumn and winter. People whi shoot rabbits down in the McKenzie and Central might know more from experience …

It's ducking cold around here at the moment. Running the 223 suppressor on the 22 is useful (more volume) Between the cold and high-ish elevation (200-300m) it's not unusual to have 2 in 10 rounds go 'crack' rather than 'woosh'.
the 18650 batteries don't last as long in the winter, tend to get about 4hrs out of a pair before needing to swap them out.