A #11 percussion cap looks like a small cup made of very thin copper that is placed over a steel nipple in the rifle's breechplug. It is ignited by being struck with a flat-faced hammer or striker (which is the case with the BuckHunter). If you have a Buckhunter like mine, then it probably has a #11 nipple (I replaced mine with a musket nipple, however). A 209 primer is the type of primer used to ignite shotshells. They have a dome-shaped top that the firing pin strikes, and on the opposite site they have a small hole where the flame comes out when ignited. 209 primers are inserted into a recession in the breechplug and fired with a firing pin.

#11 Percussion Caps:


Muzzleloader nipples (far right is a #11 nipple, second from right is a musket nipple):


209 Shotshell Primers:


I have a Traditions Buckhunter Pro in nickel. It was the first muzzleloader I got to shoot 1" groups at 100 yards, but I was shooting the now-discontinued 410gr Hornady Great Plains FN conical. I haven't shot it in years, and it's sitting scopeless (with rings on) and I can't find the breechplug wrench. It was my second ML, and the first ML I shot a deer with.

I hope this info answers your question.

Mike