I own a Pietta 1851 Navy Colt, and a Connecticut Valley Arms .50 cal. Hawken rifle. Haven't fired them in several years, though.

I have both Pietta and CVA guns. The only part that is annoying is the local shops don't stock much for BP, so I have to drive to Cabelas in Hartford. I'm using 777 as my powder. It's a little hotter, so I back it down by 5-10 grains.

I've been into shooting flintlock rifles and pistols since the Seventies. Most of mine I've built myself using components from Track of the Wolf and Muzzle Loader's Supply. I prefer Siler locks and Colerain barrels, and like to use black walnut for my stocks.
To me, what is amusing is to hear some of the shooters with their black plastic guns complaining about your humble stinking up the range with his "Obama Guns". They eventually shut up when they notice that, while they were fire-hosing hundreds of rounds in the general direction of their targets, I was slowly and methodically putting ten round balls into the bullseye.

Though even in Connecticut the regulations are nonexistent on them. You can buy any antique design (prior to 1898) online or in a store, no back ground check or any paperwork needed. Very different experience compared to smokeless designs.