NovaProspect

I am looking into buying my first shotgun for clay pigeon shooting/HD, and I am considering an 18" Supernova. I realize the shotgun will hold 4+1 shells, and with a TacStar tube extension it can be boosted to 7+1. My question is, can it hold 7 3.5", 3", or 2.75" shells? It would seem like common sense that you may be able to hold 8 or 9 of the shorter shells compared to the 3.5", but I cannot find anything that explicitly says this is the case. Any other advice for a soon-to-be shotgun owner is appreciated.