Benelli USA just goes by U.S. import regulations & laws. The real blame for Reg. 922(r) should go to the ATF & Politicians who create these poorly designed rules .
I think American gun manufactures were upset that their gun sales were losing to imported war surplus firearms coming into the US. So they had their lobbyists propose laws to try to beat out their competition.
I've have mostly used Federal & Remington Shells. Recently picked up Some RC Tiro A Palla slugs( Stuff from Italy) to try out . Only stuff i could find locally for now.