Brandon, is that the flush mount .575? I put a Carlson flush mount .575 on one of my son's Benelli Novas, and he gets mid 200s with the 1-7/16 oz load, while my other son put an Undertaker on his and gets high 200s with that same load. Out of my Rem 870, I get 260ish with that load and 320+ with the 1-5/8 oz load, and 375ish with the 1-7/8 oz load. The Benelli/Undertaker gives 300+ with the 1-5/8 oz load. Those all have 26" barrels, which is what I like for the 20 gauge.