Generally most 3.5" guns will handle all 3 std sizes. Even autoloaders. But generally need 3 dram loads to work for 2.75" shells. Soft recoiling, skeet loads like estate, etc, might not cycle well. But most trap shooting I do is single shot anyway.

That said, I was pleasantly surprised to see my browning gold 3.5" goose gun cycles 2.75" 2 dram loads perfectly. Its not supposed too.