As has been well documented in the Double gun Journal, shooting 2-3/4 in shells in a 2-1/2 chamber is not a problem. If it were my gun I'd do what I always do in old damascus barreled guns (that are in good shape) and shoot Winchester AA Low Recoil/Low Noise shells in it.
Steve


Approach life like you do a yellow light - RUN IT! (Gail T.)