I use a CGW 11.5# mainspring, CGW extended FP in my Shadow and have never had a light strike with a Tula spp yet. Nor Winchester, Federal, Magtech or Tula srp. The only misfires I've had were due to the gouge in my LnL where the primer punch has cratered my press frame and my primers were not seated low enough. A second trigger pull and away they go...
Tempted to try an 8.5# spring just for fun, my SA trigger pull is under 3# with the 11.5# spring right now, I wonder what it would be with the 8.5#er?