Shooting my Pietta 1860 Army in competition, I have found that the best way to insure repeatable accuracy, point of impact, and reliability (cylinder not jamming) was to use an .006 automobile feeler gauge. (the ones we used to adjust the rocker arms and tappets on automoblie engines like 1955 Chevys)
I put the hammer on half cock, screw the "wedge screw" in all the way so it doesn't interfere, and slide the feeler gauge between cylinder face and barrel while tapping in the wedge. Once I get a nice friction fit, I bring out the wedge screw to contact the little shelf on the wedge and hold the adjustment. If your wedge is battered it won't hold any kind of accurate barrel cylinder gap and accuracy will suffer.