I was hunting with my muzzle loader in NW Florida this afternoon. Keep in mind that my gun is deadly at 100 yards. A huge buck steps out at about 100 yards and I was steady and waited on the perfect shot. When I fired, my gun barely made a noise, but it was more than just the cap going off. (I know what a misfire is) I found a small patch of white hair where the buck was. Is it possible for only one of the two powder pellets to fire? That's the only thing I could think of and that's why my bullet was so low.

Yes

The flash hole was probably partially clogged. Did you fire a primer before you loaded it ?

That sucks

Black powder substitutes can go bad with age and exposure. Would that be a possibility?

I usually fire a primer but I had just cleaned the plug and blew it dry with a blow dryer. I feel certain only one of the two powder pellets discharged. I had four nice rack bucks using that area every day and knew I was going to get a shot. I didn't expect one that big to show up. I never had him on camera.

Sounds like your lower pellet got wet (possibly with oil that settled on top of the breech plug) and the top pellet fired

There are no big bucks in Florida lol jk man that sux possible got moisture to the pellets

I'm sure I just barely grazed him. There was no blood with the white belly hair. He will probably show up again soon I hope! I definitely have him on my trail cam. I am going to pick that up tomorrow. Thanks for the replies.

Just for grins and giggles I didn't unload mine last year (.45 cal Hawken) and hung it on the wall still capped but with a piece of leather between the hammer and cap. In a basement, no AC but does have a dehumidifier. Took it down at start of mussel loader season this year, stepped outside, set up a target, aimed, pulled trigger and BOOM! They can be picky though.