It's Federal law,(Gun Act of 1934) that shotgun bbls must be at least 18" measured from the muzzle to the breech face. Overall length must be at least 27".
As for Pistol grips, I know of no serious WIHTF types with one except for Class III shorties suitable only for extreme CQ work, and darn few of those.
Hip shooting used to be part of our qualifier course and I've fired hundreds of rounds that way. If it does hit the fan, I'll shoot from the shoulder using the sights at anything more than contact range.
