Designed during the late 1970’s this is one of eight IMSA calibers in the series, with the smallest being the .25, followed by the 6.5mm, 270, 7mm, 30, 8mm, 338, and 35. The original designs by Elgin Gates were based on the 300 Savage case with the shoulder moved back and with a slightly different shoulder angle. Federal made a few runs of cases for Elgin as a “basic” case, with the ram in the headstamp, although the original version of the ram was called a Borrego, or sheep as the sport of Silhuetas Metallicas originated in Mexico just after WW2. It was when the sport started in the US that the sheep was changed to a ram. (Brandt Ref. 338B).
