Spadone, let me add to that. With a pre-threaded, short chambered barrel, assuming the shank length is correct for your particular action do the following: Disassemble the bolt. Install the barrel. Try closing the bolt body on a go gage. It should not close. With the correct chamber reamer, an extension, and T-handle, ream the chamber just a little at a time until the bolt body will close on the go gage with a very slight feel. It should lack at least a quarter inch from closing on a no-go gage. George