The .375 and .459 Elsa "K" Magnums were the work of Dr. Lauren Kortz proprietor of Elko Arms, Belgium. Made for double and combination guns in Ferlach, Austria.

He offered both rimmed and rimless cartridges, the former having a case length of 3.3 inches and termed "Super Magnums" and the 3.25" Regular elsa "K" Magnum.

Kortz claimed a 200 fps increase over the nearest factory rivals , .375 H&H amnd .458 Win.

Ammunition was supposedly developed i n the U.S sometime in the early 1980's.

That is all I have I am afrain,m hope it helps.