when I was still shooting USPSA matches. We would have side matches, shooting steel/pepper poppers with shotguns. Bcause of the turn out, we had classes, and an overall winner. Major Shotgun (12 Ga.) and Minor shotgun (20 Ga.). We found, that the different between the 12 & 20 was very little to none, But the differents between Semi and Pump was huge, so big in fact that the Major/Minor was dropped, and was replaced with a Pumper Class and a Semi Class. After we had a Pump-Winner and a Semi-Winner. We would then change the course around and the top Pumper and the top Semi would shoot-off for overall winner. The 20 ga. semi dominated these matches.