The FP is the base model, it has a Savage synthetic stock, No accu-stock no detachable magazine. The FCP give you an option of a better stock, from either McMillan, HS precision, and one time choate. The FCP k is an accu stock with a break. All of them have a detachable magazine. (I don't believe this was true before 2006) Ultimately they are all the same gun, just a stock difference. The accu-stock guns, use a different bolt release, recoil lug, and barrel nut.