How long has that existed? I have never heard of it before but it sounds like an absolute mid size game crusher!Case length about halfway between 300BO and 223 (1.530"); 223 parent case; .277 bullet. Shooting 90 gr Nosler Bonded Base around 2700ish, the kids and I have killed a bunch of deer, coyotes and even a bobcat or two with them in the last 10 years. Plus they are easy to load subsonics in using 270 Win bullets like the 150 grainers.