Shot my 1187 20 ga. 26inch barrel today. I shot the RSF, GSX and a SSX, using Hevi-13 #7's, Fed Hvy Wgt #7's and the Mag Blends. All shots were at a measured 40 yds, temps in the 60's and unpolished, dirty barrel. Results below.
Hevi-13- #7's - SSX -152 in the 10"
Fed Hvy Wgt #7's - SSX 172 in the 10
Mag Blends - SSX - 86 in the 10
H-13 #7's- RSF- 122
Fed #7-RSF- 147
Mag Blends- RSF- not worth counting.
GSX patterns were splotchy and did not compare with the other two chokes.
Conclusion: I finally found a load that even the SSX doesn't pattern well, the Mag Blends. After the great results i got with the 12ga. Mag blends, i was hoping for a better showing. I am again impressed with the SSX choke tubes. I think it would be hard to beat this choke as a starting point for folks looking to improve their patterns.
I think my patterns will improve a good bit after a barrel polish, But i wouldn't hesitate to take a 40 yd shot with either the RSF or SSX using either of the heavier than lead # 7 loads. Will post results again after barrel polishing.