I started on one, even bought the trim die to make the brass. the round is about the same as the 30 bench rest. the BR round/brass replaced the 308 Barnes for the most part when quality 7mm BR became avaliable there is not a lot of case taper to aid feeding or extraction. I formed some brass (not full length sized) and it wont work in a standard mag it might work in a modifed 223 or 5.45 mag.I keep wondering why no one tries the .308 Barnes kurtz.
rechambering could be done on non chrome lined barrel and the round can be loaded with .310 bullets if the chamber has a large enough throat for the additonal OD. dies and reamers are avaliable. the 308x1.5 Barnes is also done in a shorter and longer version and also in every thing from .17 up to .35 calibur. I was looking into a 6.5 version.
the the new 30 RAR round is simular but with even more capacity made from a 284 case with a rebated rim.
I shelved the project when I decided if I was going to load up to 52,000 PSI I would just build a full size 308 Win and take advantage of the addditional case capacity and already made brass and get the same results with less pressure. the AK can be be built with full length 308 brass pretty easly so it dont really make sence for me at least to form brass and trim it and mess with mags for a shorter round.
It would be a great AR round if the pressures were kept safe.
it can give 2640 FPS with a 125GR bullet and 2500 FPS with a 150 GR bullet according to the designer the late Frank Barnes in the Cartriges of the World book this is a good improvement over the x39 but it also runs at much higher pressures.
Im pretty sure I started a thread on it around 3 or 4 years ago. and there was a fair amount of discussion.
pistol silhouette shooters have been using the 308 x1.5 or simular versions for years.
for hunting it out performs the 30-30 hands down and is in the 300 savage range of power