I will not take metal out of the inside of any shotgun barrel. I don't care how short the chambers are, I can make shotgun shells that will work just fine. Sherman Bell's actual comment on long shells in short chambers is "The pressure rise in very small. Shoot shells that don't exceed the pressure range that is proper for the gun, regardless of the length of the shell." Using that thinking, I load and shoot 2 3/4" shells in 2 1/2" chambers when I feel like it, but load them to low pressure and reasonable shot charge. Right now, I'm way ahead in loading 2 1/2" shells, have plenty, so I don't worry about 2 3/4" shells. By the way, my 375 Ponsness Warren is a standard 2 3/4" loader with a sizing die that I made myself from a standard 2 3/4" die. That is the only modification and didn't cost me a cent. I probably paid about $65.00 for the loader 35 or 40 years ago.