The answer is of course branding (6 ARC vs. 6 Grendel)
But also you should be asking .... of all the new 6mm cartridges which one ?
6 ARC - 2750 FPS
6 GT - 3000 FPS
6 Creed - 3100 FPS
Which one you want to mess with...
Platform wise - only a few of us can make AR’s that shoot close to a Bolt gun so an AR for 400+ meters that match a bolt’s accuracy generally don’t occur in mass qualities.
Brass - all but the GT is offered by Lapua
Bullets - they are all 6mm
So it comes down to platform & how long you want the barrel to last.
