6.8 spc vs 300 blk question

[HokieCasey]

First let me say I already have a 16" blackout that I reload for. An I know there AR some strong opinions on non 5.56 caliber ARs.

Comparing loadings between the two calibers I can't figure out what the practical difference s between the two. For equivalent bullet weight it looks to be only a marginal velocity increase.

What I'm trying to figure out is if I should go ahead and build a 6.8 spc around a 18" ml black hole barrel or should I sell the barrel and plan to swap to an 308 AR if I need something stronger?

Anyone have any thoughts?

 

[BradMacc82]

If you plan on reloading for the 6.8, sure why not build one? AFAIK you don't gain much/if anything once you get past 16" with the 6.8 (could be wrong though).

I'd just go with a AR-10/SR-25 type build and call it a day, ammo's plentiful.

 

[HokieCasey]

Yea that's just it. I already have an 308 AR. And if I wanted long range I'd probably build something that uses a 308 pattern if not 308.

 

[BradMacc82]

The only practical difference I see between 6.8 AR and a AR-10 type, is .30 cal in a lighter weight platform.