Usually if a rifle fails to fire, hangfires or misfires, I would examine the reason as to why this might be happening. Then correct that problem. Musket caps produce a large amount of flame into the breech of the rifle which should produce reliable ignition no matter what. Fix your favorite rifle and use it. In the mean time until you get the rifle fixed take the one your sure will go off, unless accuracy is a real concern. If you feel the 209 accuracy wise can not do the job, then even though it will go off every time there is no use depending on the rifle for that critical shot.

Before you load your Traditions centennial thumbhole with the musket nipple, make sure that the breech of the rifle is clean and dry. No excess oils or bore butter or anything down there. Swab that barrel with isopropyl alcohol before loading, then some dry patches. This will make the bore ready. Now put a clean white patch on your cleaning jag and push it to the bottom of the breech. Now pop a musket cap. Pull the patch and check it. If it is not blackened, then there is a problem in the musket nipple or the bolster area of the rifle. You then need to clean thoses area and replace the nipple with a hot shot type nipple.

Another question is what kind of powder are you shooting? If it is pellets, get ride of it and go to loose powder. Loose powder ignites much easier then pellets. If you're burning a synthetic powder like Triple Se7en and Pyrodex then try some Goex FFFg black powder. Black Powder lights off much faster and easier then the synthetic powders.

Good luck when that big monster mossy horn walks out in front of you.....