6.8 spc ad AR lower questions

[crowdedsilence]

So I'm looking at picking up an AR styled rifle, but im having a hard time deciding between an AR and a rifle i could hunt with. So i looked into armalite AR-10's, but they get a little pricey. I found on gunbroker you can get an AR upper in 6.8spc for a decant price.
Does anyone know if the 6.8 uppers will fit on any AR lowers or do i need to find a matching lower?

Also does anyone know where i would find something like this locally?

[Jeffro600]

I believe they will fit and function with any normal AR lower...youll have to find magazines for them though if the upper doesnt come with any.

[Rott Weiler]

I have some 6.8 uppers. I carry CMMG and LMT. I don't have them listed on my website yet (the website link is below). I also carry the 6.8 mags. Send me a PM if you want more details and pricing.

Scott

[karstman]

I've got an AR in 6.8 SPC. Killed an antelope with it this fall. The upper will mate with any standard lower. Only other needed items are the 6.8 bolt, and 6.8 mags. If I did it again, I'd want a mid-length gas system. It gives a little longer sight radius with the irons, and dampens the recoil just a bit.

C-products mags feed 100% in mine. Ammo can be hard to find locally, so either load your own or check out silver state armory.

[ZappBranigan]

Isn't the 6.8 just a necked-up 5.56? In that case, wouldn't a standard M16 magazine (maybe with a different follower) work?

[Jeffro600]

Isn't the 6.8 just a necked-up 5.56?

No, its quite a bit different in all dimensions...it is based off of the 30 Remington case.

[Jake_Blues]

You might also consider the 6.5 Grendel cartridge. It offers considerably more energy, especially as range increases, over either the 5.56 NATO or 6.8 SPC.

Here's a link to some sample ballistics comparisons of the 5.56, 7.62, 68 SPC, and 6.5 Grendel:

Comparison PDF (http://shootersforum.com/attachment.htm?attachmentid=446&d=1076081272)

-E

[bcw1284]

I'm pretty sure there are conversion followers out there to use 6.8spc in older ar/m-16 mags. no idea on their reliability.

there are some 10 and a few elusive 20rd mags out there for 7.62x39 ar's, but the 20 rounders are out of production from what I can tell. not sure what the holdup is.

also, keep an eye out as wilson (and others) may be comming out with a 5.45 (think ak-74) ar-15 barrel & bolt head, which would use standard ar upper/lower/mags. the hk m-16 mags have been tested to feed all 30 rounds of 5.45 without fault, whereas other mags would not. this is using the existing 5.56 nato follower also.

if you want to go .308, check out DPMS. they have much better (and IMHO cooler) ar-10 models than armalite. cheaper mags too.

[TW]

I could be wrong (and usually am :P) but I thought one of the advantages was that the 5.56 mags could be used.

Dr. Gary Roberts on Lightfighter, 10-8, M4Carbine and a few other boards has done some extensive ballistics testing with the 6.8spc. It would be worth searching.

[karstman]

5.56 mags will NOT work with the 6.8. It's not just the follower that is different, the two shallow grooves in the 5.56 are much more shallow in the 6.8 mags.

[TW]

Here is some ammo results and thoughts from Dr. Gary Roberts.

"Some random thoughts on the terminal performance characteristics of some of the more common projectiles in 6.8 mm:

Barnes 85 and 110 gr TSX JHP -- These all copper, lead free bullets bullets offer good expansion and penetration. They would be useful as both an LE barrier load and for hunting medium game.

Hornady 110 gr VMAX PT -- This is a great fragmenting bullet and is perfect for CQB/LE SWAT entry work; it is also a good choice for light to medium game.

Hornady 110 gr OTM (loaded by Hornady) -- This is good fragmenting bullet for military use where PT bullets like the AMAX are prohibited, as it offers similar terminal performance to the 110 gr AMAX. It has better glass performance than the 115 gr OTM.

Hornady 115 gr OTM (loaded by Remington) -- This load has dominated recent military terminal performance testing because of it�s early yaw and superb fragmentation, even at reduced impact velocities.

Remington 115 gr JSP -- Good expansion and penetration make this an excellent choice for law enforcement use through glass and other intermediate barriers, as well as into vehicles. It is also an excellent choice for hunting medium size game.

Sierra 110 gr Pro Hunter JSP -- This is a good bullet for law enforcement use through glass and other intermediate barriers and would be a great load for Highway Patrol and State Police who are working primarily around vehicles. It is also a great hunting load for medium size game.

Sierra 115 gr OTM w/cannelure -- This second generation SMK offers improved feeding reliability and much more consistent terminal performance with early yaw and ideal fragmentation. It is a good choice for military combat and non-barrier LE use.

Sierra 115 gr OTM w/o cannelure -- This first generation SMK is very accurate, but offers somewhat variable terminal performance and is not a great combat, LE, or hunting choice--it is best suited for match target shooting.

X-Treme bullets 115 gr TMJ -- This bullet offers very good soft tissue terminal performance, however, like many FMJ and OTM loads, performance through glass is not great. There have been some issues with pressure spikes using this load in undersize chambers, as well as some dimensional variances.

With the projectiles discussed above, a 1/12 twist barrel is probably the best choice!

SSA has developed two true AP loads, a 97.5 gr tungsten penetrator similar to M993/M995 and another using a hardened steel penetrator like the old .30-06 M2 AP �black-tip�.

Note: Most of the 6.8 mm bullets are continuing to upset down to at least 2100 f/s

It is very important to keep in mind that the proper 6.8 mm velocity is 2600 fps +/- 50 fps for 110-115 gr projectiles when fired from a 16" barrel. Government organizations who purchase 6.8 mm should specify in their purchase contracts a minimum acceptable velocity of 2500 fps with an objective velocity of 2600 fps for 16" barrels firing the 110-115 gr projectiles. For duty use, flash suppressed powder, crimped primer, waterproofing, and bullet cannelure should be mandatory requirements."
Here is a good article on the 6.8spc.
http://demigod.org/~zak/archive/sgn_68spc.pdf (http://www.colorado4x4.org/vbb/index.php?q=aHR0cDovL2RlbWlnb2Qub3JnL356YWsvYXJjaGl2ZS9zZ25fNjhzcGMucGRm)

Enjoy.