BrentD is right; the earliest Winchester Single Shots marked .25-20 are .25-20 Single Shot. But then they started marking them .25-20 WCF. And they were still .25-20 Single Shot. And then, when what we call the .25-20 WCF (the shorter, "Repeater" cartridge based on the .32-20 WCF) came out in 1894 or 1895, they marked some ".25 Winchester"--the few I've seen were all .25-20 WCF, the "Repeater" version, that is. Confused yet? (Especially confusing since some of them were on Highwall receivers and those were also used for .25-35s....).
The very last bunch, mainly a cleanup of unused receivers after WWI, were made in the "Repeater" chambering and marked ".25-20 WCF". Unfortunately they stopped making them around 1919 or 1920, made up the majority of spare parts into finished guns and sold them off over the next few years; no more confusion, alas.
Good advice on staying away from hot reloads in a Stevens 44. They aren't prone to catastrophic "blowup" type failures but will shoot loose in a hurry if you try to imitate the old .25-20 WCF "High Speed" loads. The limitation isn't really the metallurgy, it's the design. They look like, but aren't true falling blocks; more like a weaker version of the rolling block. Very neat rifles. I have one in .22 WRF that I got for cleaning out a neighbor's sheep shed back in the late 1940s. It had a badly leaded bore from shooting .22 LR birdshot shells in it, but a local gunsmith showed me how to "get the lead out," and I've been shooting it ever since!
