A tale of two cylinders: a conversion cylinder of a different caliber increases the flexibility of a single action revolver.
It's worth noting that not all cylinders are alike. I purchased two .45 ACP cylinders found on eBay that were advertised as having come from old-model Blackhawks. I can't help but wonder what happened to the original revolver and how the cylinder became separated from it. When I started this project I made a rash assumption--and we all know what happens when we make assumptions. I had assumed that all Ruger cylinders were manufactured to the same specification. Perhaps I didn't hear the game-show buzzer going off indicating I had guessed incorrectly but my two new cylinders were as different as night and day. Both chambered .45 ACP cartridges, were fluted, and came from Ruger single action revolvers, however, that's about where the similarities ended.
The first cylinder I purchased, which I called cylinder #1, came in a red felt bag as originally provided by Ruger. The problem with these bags is they absorb moisture. Most people never removed the spare cylinder from the bag and the cylinder eventually develops rust. This cylinder had almost no bluing left and had plenty of rust spots from being stored in the felt bag. In case you're wondering, I did not save the red bag because it had too many holes in it where it touched the cylinder, causing rust. This cylinder had been fired at one time and was stored without being cleaned. It measured 0.740 inches in length and the ratchet measured 0.611 inches in diameter. The rim of a dummy cartridge set flush with the rear face of this cylinder.
Cylinder #2 was in pristine condition, cleaned and all of the bluing was intact. I knew it had been installed in a revolver at one time because it had the drag ring caused by the cylinder latch. To my surprise this cylinder was shorter; it measured 0.700" long and the ratchet measured 0.577". When I inserted a dummy cartridge into one of the chambers, the rim was exposed, sitting above the rear face of the cylinder.
Milling The Cylinders
I wanted both cylinders to be the same as the original .45 LC cylinders that came with my two Vaqueros. I measured the original cylinders and found they measured 0.700" in length and their ratchets measured 0.560" in diameter. This meant that I would need to reduce the diameter of the ratchet of each new cylinder and reduce the length of cylinder #1 by 0.040".
I measured the gas ring of each new cylinder and they both measured 0.435" wide by 0.095" high, so I milled a 0.436 hole 0.200 deep in a piece of aluminum mounted to my older MAXNC-10CL (maxnc.net) hobby CNC mill. I then drilled and tapped a 1/4-20 hole in the center of this hole. I placed a piece of 1/4-20 threaded rod through the pivot hole of cylinder #1 and screwed the rod into the threaded hole. I installed a 1/4-20 nut onto the threaded rod to hold the cylinder in place. Using a 1/4" square-end milling bit, I programmed the CNC mill to reduce the diameter of the ratchet and mill the rear face of the cylinder. I used the same program to reduce the diameter of the ratchet of cylinder #2, but because this cylinder was already the proper length, no metal was removed from the rear face.
Both cylinders had end shake issues. Cylinder #1 had an end shake gap of 0.030" and cylinder #2 had an end shake gap of 0.014. Excessive end shake causes the cylinder to move forward and rub against the rear of the barrel and can induce misfires by the primer moving away from the firing pin. End shake can easily be corrected by installing an end shake shim. Brownells sells a 10-pak of 0.0045" Single Action Revolver Gas Ring Shims (#713-000-080) which I could have stacked to fit. Since I have a CNC mill I fabricated my own using a piece of 3/64 tool steel. I milled the two end shake shims I needed 0.436" in diameter with a center hole of 0.270". I installed the 0.030" shim onto the front of cylinder #1 and the 0.014" shim onto the front of cylinder #2.1 used Super Glue Gel to hold the shims in place so I don't have to worry about losing them when removing the cylinder.
Refinishing Cylinder #1
I am a big fan of cold-bluing. I have done complete receivers with cold blue solutions and they have come out looking very nice. After reducing the diameter of the ratchet of cylinder #2 I cold-blued it to protect the exposed metal. For cylinder #11 wanted to try a different process using Brownells Dicropan IM. Rather than using hot bluing salts and a single dip process, Dicropan IM is a slower rust-bluing process that requires multiple repeat dipping and carding.
Brownells sells a complete Dicropan IM bluing kit (#082-905-105) but I already had most of the components, so I purchased just what I needed: One quart of Dicropan IM (#082-008032), 400-grit polishing compound (#080-505-400), and a soft stainless-steel wire wheel (#360-164-631.) The wire wheel is used to brush off the surface rust ("carding") caused by the rust-bluing process. The Dicropan IM instructions say to use degreased steel wool for the carding process, but the wire wheel will helped card the front and rear faces of the cylinder. I already had Brownells TCE (#083-060-032) for cleaning and degreasing, and my wife purchased a cast-iron pot at Goodwill that was deep enough to submerge the cylinder so I was pretty much ready to go. I degreased two pads of 000 steel wool by unrolling a small piece and soaking it in TCE and then dried it with a paper towel.
As with all forms of finish, preparation is everything! I wanted to remove as much of the rust, pits, and old bluing from cylinder #1 as I possibly could. Rust pit exist due to rust being a corrosive process which eats away metal. Bluing is a process that only partially protects steel against rust. It is a passive outer coating of corrosion and is named after the blue/black appearance of the finish. However, blued steel must be treated with a water-displacing oil to reduce wetting and the galvanic action that causes rust.
I installed a 1/4-20 threaded rod through the pivot hole of the cylinder and held it in place with a nut and washer on either end. This rod allowed me to secure the cylinder for polishing. I installed one end of the threaded rod into my padded vise and used strips of 220-grit, then 400-grit wet/dry sand paper and "shoe-shined" the cylinder. When one area of the cylinder became smooth and the old bluing was removed, I rotated the cylinder to work on another area. I polished completely around the cylinder until it was free of the old bluing and most of the pits were removed. I couldn't remove all of the pits because some of them were very deep and I didn't want to remove that much metal. I installed a felt buffing wheel onto a drill and coated the wheel with the 400-grit polishing compound to finish polishing the cylinder.
After the cylinder was polished I followed the Dicropan IM instructions. I completely degreased the cylinder with TCE, then suspended the cleaned and degreased cylinder in a pot of boiling water for 15 minutes. I drilled a hole in a flat piece of wood to prevent the cylinder from tipping over in the pot. After boiling, I removed the cylinder from the water and shook the excess water. The cylinder was so hot that most of the water evaporated. I used a pad of degreased 000 steel wool to remove any surface rust that appeared, then used a large swab to coat the cylinder with the Dicropan IM. The exposed metal immediately turned dark black.
I liberally applied the Dicropan IM for one minute, then immersed the cylinder into the boiling water for another five minutes. I again removed the cylinder and shook off the excess water and allowed it to air dry. The cylinder had a thick, orange-colored coating that I carded off with the degreased steel wool. I threw away this steel wool and the first swab. After carding the cylinder was a shiny light blue/black in color. With Dicropan IM, more applications makes the bluing darker.
I applied 12 more coats of Dicropan IM. After applying each coat I boiled the cylinder for five minutes, removed it from the water, shook off the excess water, and allowed it to air dry. After the cylinder dried it had a white coating which I carded off with a second degreased pad of 000 steel wool. It took nine coats before the cylinder started to take on a darker color, so I did four more applications to get the nice dark color I was looking for. I soaked the cylinder in a water-displacing oil overnight to allow the bluing to cure. The only way I could tell the Dicropan IM-blued cylinder from the factory-blued cylinder was the newly finished cylinder did not have a drag ring caused by the cylinder latch.
To finish the job I took an electric engraver and engraved the last three digits of the Vaquero's serial number on the front face of each cylinder similar to the way Ruger does at the factory so I can tell which cylinder goes with which gun. I have now doubled the versatility of my two .45 LC Vaqueros by providing a .45 ACP conversion cylinder for each one, and hopefully increased the value of each revolver as well.