The first mossberg 930spx i had, i put about 200 rounds of sporting clays shells...just to break it in, and to see if it will handle that light of a load...I gotta admit it looked weird, but oh well it was fun shooting clays with no choke and short barrel.
At my indoor range, they only allow slugs from shotguns...no bird shot or buck shot....its a bummer.
Enjoy your spx....