Louis, any shotgun that has a certain length chamber, such as 3 inch, can fire that length and ANY shorter length shell without issue. Cheers and stay safe!

3 and 2.75.

You can use 3" and under shells in a shotgun chambered to accept 3" shells but you can't use 3" shells in a shotgun designed to accept 2¾" shells. Using 3 in a 2 3/4 if you do, the rolled or star crimp at end of case will unfold and have nowhere to go in the short chamber. it will obstruct the bore and cause the wad to hang up, increasing pressure dramatically. possible catastrophic result. much too close to the shooter's face to find out.