RE: No more hangfires with real BP.............
A .50 round ball ahead of 50 to 70 grains of BP is plenty if you put it in the right place. Double-lung or heart shotand the deer will go down quickly.
Odd as it might sound, I've had less rust problems with BP than 777. With 777 I was sometimes finding an orange coloration on drypatches run downbore a day or two after cleaning. Not serious (damaging) rust, but some oxidation was evident. I think I may have not been getting all the residue out of the bore, since it's hard to see on the patches. With BP I use the method of "pumping" water through the bore to get most of the residue, then bristle brush, then a good BP solvent. Scrub until white patches come out white! Then I use WD-40 to remove any moisture, followed by dry patches, then finish with with a good quality oil. (I like Rem Oil)
Normally I check the gun by running a dry patch downbore a day or two after cleaning, then re-oil and store it away.