They require some modifacation, I use a cutoff wheel on a dremel tool. I think you are way better off with a Lyman frizzen on your gun, but it needs to be properly installed. TC would likely replace the frizzen for you, and I hear that they have made some better frizzens lately. They would also completely check out thye lock and install their new-style hammer for you. Best bet would probably be to give TC a call.... Good luck to you whatever you decide!!