Assuming 12 gauge .020 is modified and I have always heard that is an appropriate choke for steel shot. About what "fraction" of an inch is the.020? I'm just curious being that the gun is marked IM .025. The shot clumping together and forming, in effect a solid hammer that bulges barrels is the issue, as I'm sure you know. I don't see any reason for steel shot to do better through a modified choke marked improve modified than a modified choke marked modified. Is everything factory marked and machined?