Can a 12 Ga. shotgun forcing cone be made longer? What I mean is, say 2-3/4″ made longer up to 3″ and shooting with a 3 ” shell. I do know the thickness of the barrel is considered. How much is how much to remove? Can it be done by hand with a forcing cone cutter? Can you tell me how to do this, and what to buy. I have a 12Ga 2-3/4″ I would very much like to do this to. I would like to shoot 3″ shells. This gun is a bolt action single shot. It is a full choke. The barrel is thick, and it tapers from the breach end slightly. The gun is in very good shape and clean. It has about 100 rounds fired through it. Its just a fun gun to shoot! I think this would be a good project to do! The shotgun is a Marlin model 55 bolt action, fill chock, 2-3/4″. The thickness of the barrel is .050″ at the chock, and thicker at the breech end.
I guess my first consideration would be whether the receiver will work with 3″ shells. Ejection, extraction, etc. can be issues with longer shells. So could pressure changes (not sure there’s that much between the two sizes though). I’m not sure on a bolt action, but on the pumps, like a Remington 870, Mossberg 500, Ithaca 37, etc. you usually just needed to swap a barrel to the 3″ version.
I guess part of the answer would be knowing what gun. Oh, and you’re really changing the chamber, not a forcing cone. Might ask Fred Zeglin about it and you could get the proper reamer from him too.
Answer
Yep, as the previous post mentions use a chambering reamer to deepen the chamber for 3 inch shells. Your bolt action is probably strong enough. Look to see if the same make and model were ever made in 3 inch first. Ken
