Just thinking; does it come from the magazine, having the cartridges (proper term) placed in a rack.
Agreed it's getting deep.This is getting deep.
I too am now curious as to the origin of this questionable descriptive term of which is being discussed.
Agreed it's getting deep.
Adding to the thought about the sound it makes, to me it's more
SN-I-CK SN-A-CK, rather than rack. Who wants to say "snick-snack' that 9, and let's get shoot'en."
I'm guessing it derives from the mechanical definition of a "rack", as in a "rack-and-pinion" setup, were the "rack" is a bar (usually toothed, but doesn't have to be) which moves from one extreme to another extreme in a fixed plane. But that's just a guess.