Can you fire 45 ACP cartridge in 45 colt rifle?

if 45 acp is not stamped on the barrel of your rifle then it could be chambered for the 45 long colt cartidge which would be longer and with a different rim at the base of the cartridge. 45 acp rounds were made originally for auto loading pistols. to be on the safe side you should contact a knowledgable gun dealer with this question. DONT take chances. shooting ammo in a gun that it is not designed for can be extremely dangerous.