From every thing I've read, Hamilton Bowen is a nop notch pistolsmith, same with Jim Stroh (alpha precision) Do you know if Bowen did anything other than an action job? Ruger 45 colts are well documented for tight cylinder throats, and barrel constrictions. Taylor throating is one way to relieve the constriction at the barrel threads another way is firelapping. Pros an cons about firelapping, I've had good results in 4 vaqueros, a Redhawk, and a bisley blackhawk (like the one you have) The cylinders on all the above were .447 to .449 with bores at .451. So so accuracy, after boring the cyls to .4525 and fire lapping the bores I'm getting much improved accuracy, actually better than I can shoot. Mic the cyls, and slug the bores, that would be the place to start IMO, if you don't want to bother Alpha precision can surely fix you up. Good luck. The bisley blackhawk is a fine revolver, don't give up on it yet..