I shoot BP cartridge also. If using real BP SPG is about the best. A simple check after a few rounds of the end of the barrel should be greasy if not then not enough lube. If using 777 smokeless lube works fine and you do not need as much powder. In a rifle caution using a 45 colt. Rifles were not designed to use a straight wall cartridge you need the slight bottle neck of the 44-40 38-40 or 32-20 to seal the chamber so the guts of the rifle stays cleaner and won't jam after 20 or so shots. You can use 45 just bring along some ballistol to lube and clean the lifter and such. But I found a huge difference in using a 32-20 and a 45 in a rifle. In the days of the old west they never made a rifle in 45 colt there is a reason. I made my own spg it's part bees wax part sheep fat aka lanolin pita just buy some lots easier. Just my .02 cents
What if the Hokey-Pokey really is what it's all about!