IIRC, the .25 TCU was pretty much the same thing, but the load data was based on the Thompson/Center Contender, and thus was designed around a 14-inch bbl. The .25/45 is based on a 20-inch rifle barrel. Looking at the drawings, I can't find much difference.PawPaw wrote:Just what little I've googled about that new cartridge has me wondering powerfully. Edit to add: I wonder how the Sharps differs from the .25 TCU, which was simply a necked-up .223? There is really nothing new under the sun.
If it is an existing cartridge case, it's been wildcatted. Even the 6.5 Grendel is based off of a .220 PPC, which has a 7.62x39 as the parent case, and the 6.8 SPC is based off of the elderly .30 Remington.