I checked the loading tool with an Old Army cylinder, and the cylinder pin in the Ruger is a hair smaller than the pin in the loader. (.225 to .230) To use the tool with an Old Army we'd have to either turn down the tool's pin about .010 inch, or make a new one for that gun's use. If you don't have another brand of cylinder to match, you could turn some material off the tool's cylinder pin. I might make a bushing or a new pin for open top colt size, and turn the existing pin for the Ruger and it will also fit the Remington. The thread is most likely Metric on the tool, I didn't find a match for it in my toolbox. It's diameter is like a number 12, (about .210), too large to be a 5mm, too small to be 6mm, and the thread is almost 24 pitch, so a #12-24 goes in and stalls in about 1/4 inch in. Anyway, it can be made to work.