Note on 2nd vs 3rd Generation Chambers (author unknown)
The 6.8 is only the answer when it is optimized. By that I mean it must be chambered in the 2nd or 3rd generation chambers. Ones with longer throats. The bores must also be rifled in 4 grove 1 in 11 to 1 in 12 twists. This allows loading a cartridge to higher muzzle velocities in short barreled (10 inch) and suppressed rifles without exceeding safe pressures. All the early manufacturers (and those that still don't really know what they are doing) used a SAMMI 6.8 chamber and 1 in 10 twist and blew up a lot of rifles until they down loaded the cartridges to the point that they were safe to shoot but were not very effective on the target. I would be surprised to 6.8's adopted in any large numbers.
(MUCH more 6.8 spc info coming.. page under construction still..)