Seems Les Baer has entered the race with a grendal type variant or possably the same round with a differant name. they have brass and dies avaliable.
Les Baer Custom Inc.
there also offering a 6mmx45 with brass and dies and ammo.
Id really like to build a 6mm grendal or simple 6x39 type set up on a standard AK. these are just more options. Ill add some info when I find it.
seems the grendal and the LBC are basicaly the same. with Hornady making brass this is a good thing IMOO as there will be more of it on the market.
.264 LBC-AR: A Grendel clone | The Firearm Blog
Same cartridge, as far as I know. Remember the Grendel is copyrighted, patented, and trademarked, just like the Beowulf. Which is why I have a 12.7 Schuler Short chambering reamer...
Whatever you do, don't go 6x45, you can't load the heavier bullets because of case capacity issues, and it causes troubles when used in .223 mags [the case necks are wider, so they don't stack right because AR magazines support the case necks].
If I was going to go with a AR mag length round in 6mm Id klikely go with a 6mm AR turbo or just a necked down 6mm x39 on standard x39 brass. Since I can do 243 Win fairly easy on a AK there is really no need to go with a shorter less efective round. going to want to reload with most of these new wonder rounds any way might asw ell just reload a 243 slightly light and out do all the shorter rounds IMOO.
the grendal is good round if I was stuck with a AR.