Falcon,

You got a great rifle at a great deal. Sometime back around 2000-2001, Cabela's had a closeout on their stock of Firehawks but all they had left were .58 and .32 calibers. The price was $129.95 NIB so I said "What the heck" and bought one of each. The big 58 likes FF black powder only but the .32 shoots great with Pyro P and very good with FFF black. Your .54 has the 1:38 twist and will probably perform best with a solid conical or sabot/bullet combo while both my .32 and .58 are 1:48 twist and shoot roundballs very well. I have scopes on each and the little .32 shoots as well as any of my scoped .22's out to about 35-40 yds. with 20 gr. of Pyro P, a .310 ball and .015 patch. The big .58 shoots roundballs OK and I have taken a few deer with it, but I never spent much time developing a load for it. It shoots 2-1/2 to 3" groups at 75 yds. with 80 gr. of FF black, a .570 ball and .015 patch. I tried some .58 Maxi-balls in it once and believe me, once was enough! It was not pleasant to shoot with 90 gr. FF black pushing that big hunk of lead. Both have the standard #11 nipples and I have never experienced any ignition problems with either. As 10 ga. suggests, you should use a breech cover or "bra" as he called it to protect the underside of the scope from scorch marks as the cap will burn them if you don't. I just put a layer or two of duct tape on the underside of the scope above the breech area prior to shooting and that works fine.
So get out there and enjoy your new rifle, I'm sure you'll find out it's a good shooter!

BPS