Most 3.5 will shoot 2.75,3 and 3.5. They are a bit more expensive to get the 3.5, but so are the shells. In my experience I have used the 3.5 shells very little. I do shoot the 3" shells alot more.I would say it depends on what your hunting.. Ducks in Timber 3" is plenty.. Geese in an open field a 3.5 won't hurt