Mike, the big error in modifying a gun instead of modifying the shells is that he may end up owning more than one gun.  For years, I had one eight gauge gun, made my ammunition to work in that gun.  I enjoyed shooting it, not too often, but on a somewhat regular basis.  In the last few years, I have acquired four more wonderful eight gauges that I also enjoy shooting, not too often, but on a regular basis.  I am still using the empties that I modified, in the sixties, to work in the first eight gauge I owned.  Those empties also work in the other four guns.  Now I own 30 RMC brass shells that I also use in all five guns.  Too bad about the Italian gun that is no longer suitable for RMC empties.  I would like to own a Tonolini, but I will leave it as is.