is the barrel lug drilled and tapped either on the center of the locking bolt or at the bottom of the lug? heres a picture with arrows pointed to where the barrel might be drilled and tapped for swivel mounting. if your gun is not drilled and tapped in these positions you will need to have it drilled and tapped in one of those spots or get the Uncle Mikes conversion set #'s 18102 and 18105