A large enough void to miss a flying grouse with say 7 1/2 shot?
Somebody tested this on a pattern board (somebody here, IIRC) and the results were abysmal. For EXTREMELY short ranges it would be okay, but shooting at anything near normal grouse range would be pointless. The cup and shot column were spinning in the barrel and centrifugal force threw it all apart when it left the muzzle.



























