The .25 Stevens RF was a fairly popular caliber in the early 20th century, up to WWII. Stevens made several models of their falling block single shot rifles and pistols for it. It produced about the same MV as the .22 LR HV, but with a 65 grain bullet. It was reported to be very accurate and a far better killer on small game than any .22. Some time ago, I had a Stevens rifle in .25 but sold it over 20 years ago. I have a friend who owns one, but about the only ammunition available sells for collector prices. Several years ago at a gun show, I saw two old full Western boxes on a table priced at $150 each. It might be double that today. With its heavier bullet and higher velocity, it would make an excellent revolver cartridge, but that is unlikely to ever happen unless one of the ammunition manufacturers decides to resurrect it.