I think I already know the answer to this but here it goes. I traded for a model 28 last night. But it is a 45 acp cal. The barrel says 45 1955 target if I recall properly. ( several drinks involved in this trade) so I am guessing it is a model 25 barrel and cylinder put onto the 28 frame? It does shoot well. Looks fantastic nice clean gun. Can get some pics tonight if you want