I have been using a 500 20 gauge for about 3 years now. I was using a .555 IC choke and heavy 13 6s and 7s and getting decent patterns. I know there are guys out there using sumtoy .562 chokes and getting good numbers. I have also heard that some of these chokes give good numbers TG SSX, Undertaker 570, PG Tempest 570 and 555, RSF, PG 555 Ported . I think most are shooting the fed hwt #7s also or the heavy 13 7s.I however have been bitten by the TSS bug and have been using it for about 2 years now and loading my own.