Those diameters, interestingly enough, are almost spot-on for the Stevens .25 rimfire.** The .32 Colt rimfire measures .315 body and .380 rim, which leaves me wondering how the firing pin of a .32 RF gun gets enough purchase to fire the cartridge if the .27 Ramset/Duo-Fast charge is set concentric. Does one have to enlarge or move the firing pin to make it work?
**Also same as the .17 WMR cartridge, from which, with a lot of labor and cleverness, I have been making new .25 Stevens. Sadly the WMR brass is so much heavier that the little boys' rifles I intended it for can't fire it. They were designed for copper-cased ammo. I want to assume that the same problem will exist for the .27 Ramset brass.