The first two are based somewhat off of the uzi sound effect from shadow warrior (so credits to that), but the remaining two are from a mix of various things (likely including some element of the Q2 machinegun noise though).
I know its a spriting thread, but this sorta thing tends to go hand in hand with all the assault rifles I see in here.
And ill add a sprite just in case, a pickup sprite I made for the Sniper Cannon posted earlier in the thread.
Spoiler: