I have a knight bighorn that i've had for probably close to 15 years now, and it hasn't been shot in probably 12-13 years. Someone just offered me tags to hunt their property this year but only for muzzleloader so i'm scrambling to get it up and running again. The breech plug is for open 209 and the plug's flash hole is plugged solid, and i think its beyond cleaning. I was looking at knight's website and i've found the plug for 209 with FPJ which my bighorn never used. Could i use this plug and swap over to the FPJ or do i need to buy a whole conversion kit from knight?