RE: .54 GPR and Pyrodex RS cause slight delay
RWS Dynamit Nobel 1075s are the best (red box).
If you are having so many problems with Remington & CCI-Mag caps, you need to change that nipple. They are cheap so why not change that when you buy new, smaller granule powder? Buy a Hot Shot or Splitfire nipplefrom Cabelas.... or try the 209 upgrade mentioned here.