Ed;
Note that 2 3/4" shells will firtually always fit with no problem into a shorter chamber. The nominal length is for the "Fired" shell. When the 2 3/4" shell is loaded & crimped it's actual length will be short enough to fit into the shorter chamber with no problem. Upon firing the crimp will however unfold into the cone as the fired case will be longer than the chamber. A shell with a fold or pie crimp uses more of the case length for crimping than does the older roll crimp with top wad style. When the changeover from roll to fold came about it became common practise to load the nominal 65mm load in a slightly longer case than the actual chamber. Millions of rounds have been thusly fired. It is imperative though that 2 conditions are met for this practise.
#1; The load is to be appropriate for the gun IE the load for a 65mm chambered gun should be used, not a load for the heavier 2 3/4" chmbered gun.
#2; The loaded shell should enter the chamber freely & not have the crimped end squeezed by the forcing cone, but have slight clearence at it's end.
as stated these guns are not noted for their strength & any loads fired, if it checks to be sound, should be of a light nature.
