6.8 Rem SPC and the AR-15

[WeedWacker]

From what I have been reading and what I can find, it seems the 6.8 x 43 SPC is similar in length overall as the 5.56x45. If I had a 6.8 SPC upper would I need a lower designed for it as well? Or could I use a standard 5.56x45 lower?

 

[zoomie]

Same lower for 5.56 and 6.8 SPC. You'll need 6.8 mags though for reliable feeding.

 

[WeedWacker]

How different are 6.8 mags from regular STANAG mags? is it some odd protrusion on one side (or lack thereof), different bend in the mag, or is it the follower?

 

[bigjack59]

It is basically the follower. A high quality .223 magazine will work if you don't load it all th eway full. I usually put about 18-20 6.8 in a 30 rd mag and it works fine. But to be sure it is best to invest in the 6.8 mag.

The carbine length uppers will have a LOUD bang for sure, but recoil is really nothing. It is a tremendous round, more than capable of killing deer. I have a M4 Bushmaster upper and put it on a stag arms lower I had, no problem whatsoever. The 6.8 is a GREAT round.

 

[HorseSoldier]

Primarily the follower, like bigjack59 said. I've also read that aluminum mags won't tolerate being loaded to full capacity with 6.8 Rem SPC rounds. I use steel 25 round 6.8 mags from PRI with my 6.8 set up and they run just fine -- bit pricy compared to USGI aluminum of Magpul P-Mags, though (similar cost to steel HK mags).