No minimum barrel lengths at the clubs I belong to. The open and out and no more than two in the magazine rules apply at all of them. The only other restrictions are that targets must be shot from the designated firing positions and all guns must be shot from the shoulder. The later rule is less about not permitting pistol grip only shotguns but to discourage hip shooting.
Although I have shot skeet with a 14" 870 at my club it was a stunt and I've got more suitable guns for the purpose.
Although I have shot skeet with a 14" 870 at my club it was a stunt and I've got more suitable guns for the purpose.