Ruger New Model Blackhawk Flat-Top Convertible .45

Have put the .45 Colt cylinder away for now and have started fooling with the .45 ACP cylinder.

First thing I noted was that chambers are so tight that Winchester 230 JHP factory rounds will not go far enough into the chambers to rotate the cylinder past the loading gate!

No problems with Federal 230 HydraShoks or Remington 230 grain Golden Sabres.

H&G68s which rojkoh loaded for his M1911A1 National Match pistol won't go in either, nor will my handloads with Saeco #954 Cowboy bullets which I use with full moons in my S&W 625 or S&W 3rd Model Hand Ejector Model of 1950 Military.

Seating the Cowboy bullet handloads so that the crimp groove is no longer visible, and taper crimping to .470” mouth diameter they will go in, but the as-cast, unsized bullets forced through the Lee Factory Crimp Die do not shoot as well as I would like and rojko chastised me, showing me lead shavings in the chambers when cleaning the cylinder! Oops!

Eyeballing the chambers the entrance to the cylinder throats had a distinct sharp edge where it transitions from the case mouth to the ball seat. This caused marking of bullets and can clearly be seen in the photo examples.

Measuring marked bullets on rounds which did not go in up close to the chamber mouth, the cylinder throat opening is closer to .451 than .452 and all six chambers are tighter at the chamber mouth than farther up the ball seat where a wire edge was turned up by the chambering reamer.

I decided to lap the burr out of the chamber mouths by hand instead of firing a bunch of expensive jacketed loads, as I might have been tempted to do. This would let me control the process and hand lapping vs. reaming would be more difficult to screw up!

A .30-'06 case just turns out to be of just the right diameter, with enough length to grab, turn, align and control, with a gentle taper so that you can coat it with 600 grit lapping compound, grasp in a hand drill, then carefully polish the leade entrance of the ball seat ahead of the chamber, without touching anything else. In the other photo below you can see the polished section of a lapped chamber throat where the blue is now gone for a short distance.

After some cautious cut & try, by visual examination I could clearly see the mirror-polished angle where the lap had been working, the wire-edged burr caused by the chambering reamer was also gone. I repeated the process around all six chambers, 100 turns total, 20 turns, back off, recoat the lap, insert again, repeat, repeat, wipe, inspect.

About an hour later by eye ball all six lapped chambers looked the same. So, I took six lubed, as-cast .455 Webley Mk2 bullets, dropped them into the rear ends of the chambers and drove them with a brass drift in until the bullet noses were all flush with the front of the cylinder, tapped them back out and measured them.

The origin immediately ahead of the case months measured uniformly .452, without any mouth constriction or burrs, and the original ball seat measured one diameter ahead remained unchanged at .4515". Time to load more test rounds and go to the range.

STAY TUNED!