This cartridge was likely the first of the rimless cartridges based on the G (Gründig) case type with a base of 12.55mm. It definitely precedes the 10.75×68 (M58) which is a longer neck version of this 63mm case version and is also likely to be introduced prior to the 9.3×63 (M56). It was produced by both RWS and DWM but which company introduced it first is not known. (Dixon)