I've heard rumers of various lengths being tested, but where do you stop size wise. The longest out there currently being used in the 10 gauge 3-1/2. They have restricted it to no larger than 10. I don't believe there has been a shell length restriction as manufactures have not released any longer shells or guns to the public. Cost and recoil goes up. If you can't hit them with the current ammo, then you should be picking another species to chase.
