Depends on what powder that you want to use in your muzzleloader.
If you are using BH 209 out of your muzzleloader, or shooting a Smokeless muzzleloader,. you want to use a hotter 209 primer.
Federal 209a is the hottest and used the most. CCI M, and a lot of people like the regular CCI 209 primers also.
Winchester 209 primers in the Blue box is a good primer also, it is longer in length then the others.
If you are getting blow back on to your primers when you shoot your regular muzzleloader, try these, sometimes it will take care of the blow back.