You don't have to wash your Sharps in a bucket. No wonder people think BPCR is messy.
I use the Venturino Formula of Windex All Surface With Vinegar diluted 50:50 with water. A 4 oz bottle lasts several shoots. The water does the work, a little bit of any soap or detergent is just a surfactant to help it penetrate.
I use a blow tube between shots to make the BPCR Silhouette rate of fire of 5 targets plus sighters (3 or 4) in 7 minutes. When done shooting, I blow twice as many times to soften the fouling and push a loose patch through to get out the worst of the accumulated bullet lube and fouling. Then I patch and brush with Windex til clean, being sure to get the lube star and fouling off the muzzle; and then dry and oil. A damp cloth will wipe the soot off the outside and an oily cloth will preserve the finish. Faster than getting the copper out of my .308, even including a reclean at home to get any spots I missed.
A good tight inletting job keeps the fouling out of the lockwork. You can easily pull the breechblock out of a Sharps to clean around it occasionally.
Friend of mine has been shooting a Shiloh for 15+ years plus, always with black, with that cleaning regimen and it is hard to tell from new. My Winchester seems to be holding up after about half that much use. By me, it was 100 years old when I got into BPCR.