Primer Question

[boilers]

I just purchased a used muzzle loader. It is a50 cal Black Knight. It looked like it took the 209 primer. However, I found out that it did not take the 209 primer or the #11 cap either. From what research I have done thus far it appears that it takes the four winged primer, which I have not located locally. Could this gun take thedisc plastic cap with the primer in the center? It appears as some people do not have very good luck with that type of primer, and recommend changing out the bp for one that will accept the 209 primer. Also are the bp interchangeable? Any help would be greatly appreciated. Looking forward to using this gun this upcoming deer season. Thanks