I have never used anything but the musket caps with my T/C Black Diamond and two 50 grain Pyrodex pellets. I would probably go to the 209 primer if I ever decided to load 150 grains of the pellets. I have never ( knock on Wood ) had a misfire yet.

The first musket caps I tried were ALCAN, and they were not as hot as the old Remington No. 11's I was using at the time. Later on, I got some RWS musket caps, which were supposed to be real hot. They were better than the ALCANs, but no better than the CCI #11 Magnums. I have also tried several "primer adapters", which replaced the nipple and permitted use of small rifle primers. These were surefire, but the shot-to-shot variation in velocity was significant. So I stopped using them. Finally, I got a No. 209 shotgun primer nipple replacement device from October Country, and have never found anything as sure-fire as this!! It shoots a visible flame out the muzzles of all rifles I have tried it with, and these are "drum and nipple" sidelocks. Shot-to-shot variation disappeared with this gadget, and it keeps "primer flash-blowback fouling" off the barrel breech and lock area of the stock. This is now what I use on hunting rifles.

Interesting that only one other person has seen problems with the musket caps.

Here's the idea that keeps raising it's head: No one so far has expressed dissatisfaction with the 209 primers.

I have a Knight Disc rifle and I love the 209's. I haven't had any problem with them at all. The guy that I hunt with has bighorn that uses musket caps and he doesn't have any problem with them either so it is just personal preference.

I don't care for 209 caps, I find them hard to handle. No. 11's with real black powder have never presented a problem. I have a T/C Scout that would not shoot Pyro Pellets, we thought that would be the cats meow one year, I used magnum No. 11's and it became reliable again.
Bottom line,for me, if I use loose Pyrodex or Black Powder it doesn't seem to matter what ignition source I use.

When I used musket caps they were very reliable. I had several misfires with #11's but none w/musket's. I'm using 209 primers now just because I'm shooting an Encore. Haven't had a misfire yet.

SOTHRDNK