I've got an 11-87 special purpose model for 2 3/4 and 3" shells. I've never had a single jam in nearly 10 years. However, I wonder if, since yours is built specifically for high power shells, it might have a stronger spring or other spec., such that a 2 3/4 doesn't produce enough recoil power to cycle it all the way. Do you have problems with 3" shells (I'm thinking something like a turkey load)? My guess might be that in order to handle the stress produced by 3 1/2" magnum shells, the parts have to be stiffer and stronger to keep from breaking down quickly, and so the shorter shells can't move things as much as necessary. I'm no gunsmith, so it's just a guess, but someone else here with more knowledge might check into that idea.