I have a nipple I ordered from Warren Custom Outdoor that has a screw-on cap with a floating pin in it for 209 primers. I absolutely love it. It does add another step to loading, as you have to unscrew the cap and screw it back on over the primer, but the primer is much more protected from the elements than a simple #11 cap, and the ignition power is much better than a musket cap. I bought it to see if it would cure my dad's .54 Renegade ignition problems, and I liked it enough to buy one for my Hawken. They can be found at http://www.warrencustomoutdoor.com/
. It installs with a simple allen wrench. The socket for the wrench is machined into the top of the flash hole in the nipple. A little anti-sieze grease, and it's simple to remove during cleaning. Around here, 209 primers are roughly 66% to 1/2 the cost of #11 caps. Plus, around here, #11 caps seem to be pretty seasonally offered. 209's are available 365. I like the storage of the 209s better as well. My dad also had a #11 cap fall off somewhere on his hunt last year. That won't happen with the screwed-on 209.