The Ruger Old Army is a black-powder percussion revolver introduced in 1972 by the Sturm, Ruger company and manufactured through 2008. Models were made with a 7.5" and a 5.5 inch barrel.
According to this source the revolver was tested by loading each chamber to capacity with Bullseye smokeless powder and a lead ball. While this might result in catastrophic failure in other firearms, the Old Army proved to be strong enough to handle the pressure.
As of 2023 they offer 4 options for the Ruger Old Army
- Ruger Old Army Revolver Conversion Cylinder .45LC $245.00
- Ruger Old Army Revolver Fluted Conversion Cylinder .45LC $280.00
- Ruger Old Army Revolver Stainless Conversion Cylinder .45LC $260.00
- Ruger Old Army Revolver Stainless Fluted Conversion Cylinder .45LC $295
Ammunition Caution! Recommended Ammo Specs Lead ammo that does not exceed 850 fps velocity
Never use +P ammo with these. Standard Pressure and Cowboy Action ammunition. Do not use +P ammo or any other high-pressure ammunition. The use of jacketed ammo may cause slightly more wear to the bore of the barrel than using lead bullets. DO NOT USE JACKETED AMMUNITION. DO NOT DRY FIRE.
According to this source, "stick with loads under 850 fps. Factory cowboy action ammo from HSM (200 grain lead) ran right under that limit ... Any Cowboy Action loads from Fiochi, Magtech, etc. should be fine."
To load cartridges into the conversion cylinder you need to remove the back plate and insert .45 Colt cartridges into five of the six chambers. You should always leave an empty chamber under the revolver’s hammer for safety’s sake.
From the manual:
It is not clear as to why they advise against Ultramax 45LC as the specs do not seem to exceed the limitations stated. Looking online at "Ultramax 45LC" produces sources for their Cowboy Action ammo. Here is an example:
- Ultramax Cowboy Action Ammunition 45 Colt (Long Colt) 250 Grain Lead Flat Nose Box of 250
Muzzle Velocity: 730 Feet Per Second and Muzzle Energy: 296 Foot Pounds. This is below the 850 fps limitation advised by Taylor's. The conclusion is perhaps the smokeless powder formula Ultramax uses produces such a short burn rate that could produce a pressure momentarily that would damage the cylinder. Greater pressure over a shorter duration of time would not necessarily produce a proportionate increase in muzzle energy. Pressures within the cylinder during combustion are specifically what is significant. This is not quantified and stated directly by the ammo manufacturers. This conclusion leaves us with no way to gauge other brands of Cowboy Action ammunition since manufacturers do not disclose smokeless gunpowder formula. This is why you often find gunsmiths state that you should only use blackpowder cartridges in these guns. The Ruger Old Army is in particular much stronger than other replicas on the market. The limitation imposed should be more that which the Taylor's cylinder can handle rather than the Ruger barrel and frame. Taylor's doesn't seem to like Ultramax. How can we know if any other brand has the same combustion properties as Ultramax?
sources
Related
- Black Powder Cylinder Conversion
- Taylor Ruger Old Army Revolver Conversion Cylinder