Not exactly drop in - Iver Johnson Arms Iver Johnson Barrel 1911 .45acp Threaded No Link/pin

Be sure to have a good set of files and emory cloth & a 5/32 drill bit. Had to file the sides of the barrel lugs to get it to go in the slide, inside the lugs to get the link to fit without binding and drill the link pin hole & polish the top of the hood but otherwise fit the Colt slide just fine & seems to shoot fairly well but only fired 5 rounds through it so far.