The "raised ring" design was employed by WRA and UMC. Given the cartridge, it is highly probable the case you found was made by Winchester. The absence of headstamps had little or nothing to do with proprietary designs. You will see WRA rounds loaded for "Marlin" cartridges, UMC / USC / Remington rounds loaded for "WCF" cartridges, and many of them for Sharps rounds. Partly it was a matter of technology / production methods, partly because some later rounds had such distinctive configurations that they did not need the identification.