A buffalo gun...
45 ACP can be used in both auto and revolver. The revolver must have a 45 ACP cylinder.
the S.A.S knew to put that in an AC130.
Colt 1911 .45 cal
100 or so
If you are referring to the present, today's most powerful sub-machine gun is the H&K UMP .45 cal sub-machine gun, or the Kriss Vector SMG. if you are referring to the past however then its undeniably the Tommy Gun. also a .45 cal sub-machine gun.
Gun shop, gun show, on-line firearms auction.
Gun shop, pawn shop, gun show, want ad
it depends what kind of gun you are using for example you could have a 9mm or a 45 cal. a 44 mag. a 22. a 38. there are many you can have or a 357 mag. its just depends on the caliber of the gun youre using
Check all the 1974 gun publications you can
It should be marked on the gun- something like .410/ 45 Colt.
A 9mm of some type. What markings are on it?