OK, thanks for the advice from both sides. 8B, thanks for confirming what I suspected, the gun was made to shoot 2-3/4 shells.
Ted, you hit it on the head, my feelings exactly about the gun and preserving it.
TT, I'll take your advice and shoot something else Monday. As an aside, your signature quote was the direct cause of my purchase of an AYA 3-1/2" 10ga. I have some 3" steel loads for that, perhaps it will come with me. We're planning on gunning the mud flats of East Rockaway, NY, in the shadow of Kennedy Airport.