The NSSA shoots howitzers and mortars at 100 yards' range. They shoot smoothbore guns and rifled guns at 200 yards, as far as I know.
Mortars shoot 7 shells in 45 min., then throw out two worst shots to get the score.
Guns and howitzers shoot 12 rounds in one hour; worst two are thrown out.
Rifled guns only divide their rounds between two different targets, one is a bullseye and one is a silouette cannon. The latter is now scored (so I've heard) 5 pts per hit on the barrel, 4 pts. per hit on the trail or axle, and 3 pts. per hit on a wheel.
I'm not in NSSA, am only a camp follower, and would welcome anyone confirming or correcting this info.