Well, RanchRoper --- It's been my experience that black powder just doesn't fire in freezing temperatures. Leastways, mine don't.
And it gets that cold here in South Texas for 3 - 4 days pretty near every year too !! I've been told that muzzleloaders way up north around Amarillo found a way to warm their powder up so as to keep it working in the winter, on account of they've got nothing between them and the North Pole but a couple thousand miles of prairie grass and four strands of bob wire. And maybe a little bit of Canada, which is cold enough all by itself.
I was on a job once in New Hampshire which is apparently located inside the Arctic Circle a few months every year due to Continental Drift - and I used to strike sparks with my flint `n steel and then keep `em in an empty cap box in my coat pocket for lighting my pipe and firing my rifle in the winter time. I'd just shake a few of `em out where I needed `em and than blow on `em to warm `em up enough to work. Then one day I plumb forgot to leave the cap box out on the porch rail. Just hung up my coat on the peg rack and sure enough them sparks warmed up and burnt a hole in my pocket.
In the Army they taught us to remove all oil and use dry lubricant (graphite) on our weapons in cold weather to keep them working. It worked then but I'm too old and stiff to see if it still does.
Good luck to ye.
Tanglefoot