Yes, the German ones, RWS No. 1081 are all I have ever used and most people will tell you they are the only reliable musket caps for hunting purposes. Of course finding them can be a little more difficult, I usually get them from Muzzleloader Supply in Puyallup.
I hunted for RWS for a long time, and couldn't find any.
I finally found some Schutsen musket caps. I've been very happy with them. About 120 shots down range with them the last 6 months, and no issues at all.
I've had issues with CCI and Remington caps...... I'll never use them again.
If you can't find RWS, consider Schutsen.
I'm not trying to sell more of my stock (I sold a bunch on here earlier), but if anyone wants to try them, I'll give you 20 if you can pick them up in the Auburn/Federal Way/Kent area.