Dave got me thinking about these so I bought 2 packs and took them out today. Shot them out of my 50 cal LRH percussion.
All shots were at 50 yds - swab between each shot. 3 shot groups.
Target #1; 90 gr T7 FFg - 1.67" C/C
Target #2; 90 gr FFFg - 1.55" C/C
Target #3; 90 gr FFg - 1.05" C/C
Target #4; 100 gr FFg - 0.93" C/C
Target #5; 100 g4 FFg - 0.80" C/C (additional group after sight adjustment and to verify load accuracy)
Each group had 2 shots touching and one off slightly. It was hard to pick the 'best' of the lot but the T7 and Goex FFg produce the most velocity. However the T7 was shooting very high and it is possible I could not get the POI down far enough with these sights. (I had 2 targets up and aiming at the lower target but the T7 was hitting the upper target.)

A note: 2 targets fired using Pyrodex RS and P were terrible. Bullets were all over the target. Had me totally baffled.