I've had my Ruger Old Army percussion cap & ball revolver for more than twenty years.
In my personal preference, it is made from stainless steel.
I have fired it some using black powder and round balls, but cleaning it after shooting sure takes away some of the fun when using it. Likely less than 250 shots in 20+ years.
Over time, I used it infrequently and eventually it just sat in the safe occupying valuable real estate.

But even being stainless, it is a MAJOR pain in the ass to clean it after shooting black powder or BP substitute.
I have an unusual method for cleaning it that isn't common, but it sure is effective and saves quite a bit of time, but still is much greater cleaning time than a modern smokeless powder revolver.

Recently, I considered selling the Ruger Old Army as I hadn't shot it in many years. But being they are out of production, I just couldn't sell it.

I have known about cartridge firing conversion cylinders for Ruger Old Army revolvers for a long time, but they were available in .45 Long Colt and I just didn't want to add a new caliber for one gun.

While stocking up on some shooting supplies recently, I noticed Kirst Konverter LLC now manufactures a cartridge conversion cylinder for the Ruger Old Army in .45 ACP.
And it is rated for any non plus P .45 ACP load, including using jacketed projectiles.
The Kirst unit has a non rotating cylinder back plate and one robust firing pin.
The other conversion cylinders on the market have rotating cylinder back plates and six less than robust firing pins.
I had seen some online chatter about the firing pins on the rotating cylinder back plate style having firing pin problems. (mushrooming from hammer strikes)

All of the cartridge conversion cylinders on the market in the .45 Long Colt chambering require "cowboy action shooting" power level loads and lead projectiles.
That, along with .45 Long Colt being a cartridge I don't use or own any firearms chambered in that cartridge, convinced me that .45 ACP was the more intelligent caliber choice.
I stock plenty of .45 ACP ammo, and reload for it as well.

Belt Mountain Enterprises sells a kit for using a cartridge conversion cylinder in a Ruger Old Army revolver which simplifies removing the cylinder base pin.
Since the cartridge conversion cylinder and the back plate must be removed for reloading when using the cartridge conversion cylinder, that upgrade made sense also.
All of the Ruger factory parts for ramming round lead balls into the percussion cylinder are removed, and no permanent alterations/modifications are made to the stock percussion revolver.
For converting from cartridge firing back to percussion takes less than five minutes and requires one small allen wrench for removing the Belt Mountain base pin latch kit parts.
You use the cylinder base pin or a stick to push the fired brass out of the cartridge conversion cylinder after removing the cylinder/back plate from the revolver.
This reloading issue led to the invention of the flip down loading gate and ejector rod/housing on single action revolvers.

The new Kirst Konverter cartridge conversion cylinder dropped right into the Ruger Old Army. Timing/end shake/barrel cylinder gap are perfect. It's a beautifully machined package.
I compared the new Kirst cylinder dimensionally to the factory Ruger percussion cylinder, everything is within 0.0005" so it's about perfect. (within a half thousandth of an inch)
The Belt Mountain base pin latch kit is a spring loaded assembly and it occupies the former ball rammer tunnel location. Those parts also are machined beautifully.
The Belt Mountain latch kit for the Ruger Old Army also comes with a new Keith # 5 style cylinder base pin.

The Ruger Old Army is an old model (three screw) and is not equipped with a transfer bar safety system. If you carry it, it's hammer down on an empty chamber.
So there are six chambers in the cylinder, but to carry it safely, it's actually a five shooter like a Colt Single Action Army, or any of the unmodified Ruger Old Model revolvers.

Next time I get to my local range, I will be firing the Ruger Old Army chambered in .45 ACP! Range Report soon.

Links:
https://kirstkonverter.com/
https://beltmountain.com/

IMG_20240108_130617742_HDR by cee_Kamp 32ACP, on Flickr

IMG_20240108_130646340_HDR by cee_Kamp 32ACP, on Flickr

IMG_20240108_130756072_HDR by cee_Kamp 32ACP, on Flickr

IMG_20240108_130905473_HDR by cee_Kamp 32ACP, on Flickr

Will be interested to see how it shoots. When I owned a Stainless Old Army, I just took off the grips, disassembled it and ran it through a dishwasher cycle. Made cleaning it much easier.

I cleaned it somewhat similarly.
First, preheat the kitchen oven to 225 F.
I pulled the grips, cylinder, and removed the nipples from the cylinder.
Then everything metal was tossed in the kitchen sink full of hot soapy water. (except for the grips)
Scrub the parts with a bore brush and GI style cleaning brushes.
When done cleaning, I poured a tea kettle of boiling water over all the metal parts.
Then into the oven for about two hours.
Turn the oven off and let it cool down.
The next day, oil it and put away.

Being in the middle of a cold snap prevented a range trip to the outdoor range.
However, my local club has an indoor heated 50 ft. Bullseye range. If I recall correctly, it is 10 stations wide at the firing line.
They have an oil fired furnace for heating the firing line area, and the ventilation is acceptable.
It's one dollar per person per visit when using the indoor range, and the annual family membership fee is fifty dollars.

The Ruger Old Army percussion revolver with the Kirst conversion cylinder in .45ACP had fifty rounds of .45 hardball ammo shot through it without any malfunctions or issues.
I did have to adjust the adjustable rear sight down and bottomed it out. It still shoots a bit high at 50 feet, and "pumpkin on a post" is the sight picture.

The Ruger Old Army is Bill Ruger's remake of the 1858 Remington cap and ball revolver.
The .45 ACP cartridge is at least 113 years old.

The two old timers got along just fine, however I make no claim as an expert Bullseye shooter.

IMG_20240115_145721301 by cee_Kamp 32ACP, on Flickr

I cleaned the Ruger Old Army and Kirst conversion cylinder yesterday. It sure was nice to let it sit after returning from the range and not immediately have to clean corrosive black powder fouling.
I did run into a small problem when reassembling. The Old Army doesn't have a transfer bar safety system. Cocking the hammer, it has three positions.

Hammer fully down.
Half cock.
Full cock.

When you install the conversion cylinder & back plate into the window in the cylinder frame, it has to be in the half cock position. But it's important "how" you get the revolver to half cock.
I had the hammer at full cock when cleaning under the hammer while cleaning it.
After everything was clean, I manually lowered the hammer to half cock and installed the now clean conversion cylinder and back plate into the revolver.
When attempting to install the cylinder base pin, it wasn't lining up correctly and the cylinder was stuck, and could not be removed or rotated.

I eventually figured it out and had to remove the small screw (most forward) on the right side of the frame which is the pivot point for the cylinder latch.
Removing the cylinder latch pivot screw caused the cylinder latch to drop down slightly, and with a thin machinists rule, allowed the conversion cylinder and back plate to be slid out of the revolver.

I believe there is a different interaction between the hand (which rotates the cylinder) and the cylinder latch (which stops the cylinder from rotating) when setting the hammer to half cock.
The incorrect method is lower the hammer to half cock from full cock which results in the cylinder becoming stuck, non removable, non rotatable.
The correct method is to pull the hammer back to half cock from the fully down position, which results in a fully functional revolver, and the conversion cylinder & back plate slide in and out easily.

It qualified as a learning experience!

cee_Kamp,

You made your black powder cleaning more difficult than necessary.

Water and Ballistol, window cleaner with water, or water with blue Dawn is all you need for a solvent. The oven heat procedure is also not needed.

Just for information. All Ruger old Armys require FFL for transfer due the availability of these cylinders.

clayflingythingy,

Actually, placing the revolver & parts in the oven wasn't difficult and required minimal interaction.
Was the oven procedure an extra step in the cleaning process? Without a doubt.
I was then confident there was no remaining water trapped inside any of the interior nooks & crannies.