The .25-08 wildcat first appeared in the mid to late 1950’s. Its creation was inspired by the efficient .308 Winchester cartridge and its commercial sibling, the .243. Vernon Speer, founder of Speer Bullets, suggested that a Mr. P.F Lambert of Washington D.C was the first to neck down the .308 to .257” and that for unknown reasons, dubbed the wildcat the .25 Souper. The name .25 Souper is still used to this day although it is just as common to hear the cartridge described as the .25-08. (ballisticstudies.com)