What is the difference between the #11 caps a nd the 209s?

If you saw one of each, you'd know. 209s are shotgun primers and #11s are small copper cups with priming compound in the base.

209 Primers are the same thing that sets off a shotgun shell. The #11 caps are the smalled of percussion cap ignition systems. Next are the musket caps also sometimes called Top Hats. They produce more fire then the #11 caps.

If your shooting loose powder and you have your rifle prepared correctly, I have yet to see a #11 caps that will not normally set that charge off just fine.