The 25 Don Ace cartridge is a wildcat cartridge, which means it is not standardized by any major ammunition manufacturer and is often custom-made by individual shooters or small-scale custom ammunition makers. Wildcat cartridges are typically designed to achieve specific performance characteristics that aren’t available with commercially produced ammunition. The 25 Don Ace is designed for precision shooting and possibly for hunting small to medium game due to its likely high-velocity and flat-shooting characteristics, typical of .25 caliber wildcat rounds.
Not enough detailed information is available about the specific ballistics or the exact parent case of the 25 Don Ace.