Without regard to head's rim, the approximate OD of a 2 ga. is approximately 1.35 inches. RMC uses brass rods to make hulls. They might not have the necessary diameter rods for the job and may have to special order the brass or you could find a local machinist to do it. RMC recommends Duco Cement on the edges of the seated OSC. I use RMC brass in my .410 turkey gun and follow RMC's directions regarding the Duco Cement. RMC can also make the brass reloading kit. Gil