Signed up for MTDS shotgun class and need to buy some decent training ammo that will cycle in semi auto but not break the bank (or my shoulder lol). Also need some ammo to break in new gun before class. Any recs? 2 3/4 or 3" shells. I need 250 rounds of bird shot, 50 rounds of 0000 and 20 slugs for class. Not sure how much I should shoot through new gun before class to work out any kinks etc. Slugs are GTG in smooth bore, right? Is there a minimum size bird shot for tactical class or are they all pretty much the same? Stupid questions but haven't shot slugs or trained on shot gun for home defense before. Thanks in advance.