BP can be used very effectivley with jacketed bullets. The most accurate load in my bro's .45 3-1/4" Sharps was 110gr. 2f and a 500gr. hornady RN.
At the BP velocities with that load - just over 1,350fps, the bullets didn't expand, of course, but the full length penetration in the chest and out the rump dumped a large bull moose in 10 yards of impact. That load printed 5 shots into barely larger than a cloverleaf using the tang rear sight and pin-head front sight. Shot without wiping, of course.

Lead bullets can lead to a lot of cheap shooting practise. Trouble is, in a double, they'll probably not regulate worth a hoot. With lead bullets, you need a good lube like SPG, Lyman's BP Gold or a beeswax/oil compostion. 60/40 works well in most guns. Alox lubes don't work with lead and BP.

I don't like the fake BP's due to the wide variations in velocties (pyrodex) compared to real BP. I prefer real Black Powder. I've heard, but cannot prove from my own experience that T7 will produce wide pressure extremes with full-power loads in large cases. I have some for testing, but have not done that yet. Pyrodex is a poor sub for black powder. I've had good ctg. results with Black Mag 3 - but don't know if it's available now. Still have a few pounds of it.

As Dan said, Pyrodex fouling is corrosive - to both cases and the bore. Proper cleaning maight eliminate this problem.

As to cleaning at the range, a sopping wet patch down the bore, then drying with flannel patches will clean any BP fouling from the bore.

Bullets (cast) must be oversize by .001" to .003" to prevent leading. As noted above, you have to use a good BP lube. SPG and the others work well with WW alloys up to 2,200fps in the larger bores, .45 and above using smokeless loads. In .458 bores, the Lee 500gr. with gas check is a very accurate bullet with smokeless loads. The Lyman or Lee 450gr. is a good one in .50 cal BPE's for accuracy and black powder.

Black Powder specific bullets have wide, square grease grooves. They may or may not need a lube wad beneath them, depending on the case capacity. The more powder used, the more lube needed.