TexasCHLforum.com

The 6.8SPC and 6.5 Grendel both hit harder than a standard .223; their ballistic advantage is hard to argue with.

But before you build one of those, be sure you're aware of the logistics involved; ammo and components are nowhere near as available for the two larger cartridges as they are for .223. And the guys with precision target rifles are doing quite well with the "little" caliber these days.