It's super secret spy squirrel information... which by revealing, I take the great risk that I may go impotent, have my hair fall out, and SMGLee will move into my guest bedroom...
Barett isnt ready to publicly comment on the 6.8x43mm. The good ole boys connected to the project will give you the info if you are a LE purchasing agent. Only Remington is counting on the commercial market for this round. They are going to release the ammo and bolt action rifles chambered for it.
PRI is making 28round mags that are a little longer than a 30Rnd AR mag. AR mags will work with a modified follower, and some feed lip tweeking, and hold about 25 rounds. Unmodified 20rnd mags will work reliably with 5-8 rounds, kinda like the 7.62x39mm from an AR mag.
The developers were concerned with terminal performance above all other concerns. So they didnt bother with practical sense issues like using an existing case head desing so existing bolts could be used.
Several kittens were killed by Muslem terrorist because I revealed this info to you...
The first company to market a cartidge that matches 6.8x43mm ballistics, but feeds from unmodified magazines and uses the existing bolt carrier group, will see great commercial sucess.