So I just got a Pedersoli Rocky Mountain Hawken on a screaming deal as my first muzzle loader and all I have around is some Pyrodex P since I shoot cap and ball wheelguns a lot. I shot the rifle with 72 grains of the P a few times and it seems to work really well, I was just curious if there is any long term issues with the FFFG or P powder since technically it's not the right powder. Also if anyone knows the maximum powder charge this rifle can handle that would be great thanks.

P will work all I used 'til I switched to GOEX  I have no Idea about Maxload but I used 80gP Pyrodex in a GreyHawk with a TC MaxiHunter for years with no problems.

My guess is somewhere between 50 - 80 gr should be OK in a fifty.

Keep in mind that accuracy is what your after and Velocity in a ML is not as important as we make it in CF.

When I switched to GOEX I found FFg to be best for my 50 cal and above YMMV,The rifle will tell you what it likes and with a PRB I'll bet 60gr will be good.

Thanks for the help!