Sorry you didn't get any answers yet. I think most of us have been deer hunting.
Anyway, since you have a straight line to your ignition point I don't see an ignition problem, but more importantly you may have a burn rate problem. It may be much like loading your 44 mag with H4350 instead of H110. It will ignite, but you may get 600 fps instead of 1200 fps. The opposite like loading your rifle with H110 would turn it into a bomb. With Pyrodex I do load P in my Hawken, but S in my inline. When loading P in a rifle you have to reduce loads by 10%, but it gives better ignition in a nipple and drum setup. Your going to shoot up your powder anyway so I would suggest getting the correct powder.