Not sure why the mods locked the 6.8 SPC thread below - maybe because guys started to talk about modern applications? I personally think this is one of the more interesting and under reported early GWOT stories out there, with great clone potential! If we can reopen the below thread, or combine the threads that would be great.

For AR-15 shooters and cloners of a certain age, the development of the 6.8 SPC cartridge in the 2002 timeframe was a huge deal. It was still pretty early Internet days, and a lot of the information about the round showed up first in the tactical gun magazines. (Remember when SureFire had a glossy tactical Recoil-like magazine?).  The 6.8 was a big .mil story for about a year or so, and then sort of  faded away after the MK 262 came out. Interest continued for a while mostly with hunters and some cloners, but it wasn’t ever the same.

AFAIK the only book that really discusses the topic was Bartocci’s BLACK RIFLE II. It’s an excellent book and his brief chapter on the 6.8 SPC is the best (only?) resource out there. He talks briefly through the issues and the development  – SF troops were concerned about lack of knockdown power of their 556 greentip ammo- so members of 5th SFG group and the AMU and Remington put together what became the 6.8 SPC.

As someone noted in the other thread, it would be great if some of the folks involved in the process would talk more about it. I had a couple of contacts in SF a few years after the 6.8 went away and was always surprised that no one would talk about it. The only info I was able to get was on the guns themselves: initial uppers were built in house by the AMU using PRI components ( PRI was a go-to supplier at the time as they were also building the MK12 MOD 0 SPRs then), then Barrett produced their M468 and a number of them were used (both 12” and 16” bbls), and I was told that later some LWRC M6A2s were procured COTS as well. (I had a picture of a stack of  5th SFG troopers training in front of a Hesco barrier with Barrett M468 12” uppers-will try to dig it out tonight.)

IMO the 6.8 SPC isn't just an interesting historical topic by itself, it was also an influential program in that:
1.) it highlighted the degree to which US SOCOM was increasingly willing to pursue new ammunition innovations. That’s still happening today -300 BLK, 6mm ARC, 338 LM, etc…
2.) it reignited and accelerated the “556 is too small” debate that eventually brought us the Sig MCX Spear / XM7 some 20 years later…

Would be great to keep this thread going and see if we can get some of the participants to provide some first-hand info. I don’t think it’s an Opsec issue 20+ years later?

Will

It’s an excellent topic but it’s not Vietnam or M16A1 era. It belongs in a different sub forum.

I think my 6.8spc projects are pretty retro

Really? My understanding was that this forum was all retro topics- not M16/Vietnam specific?  I’ve spent time here several times over the years on different post-Viietnam topics, including help with a couple of Operation Gothic Serpent /Black
Hawk Down (1993) clones. Ultimately I’m fine with the Mods moving it somewhere more appropriate if that’s truly the case…

There was literal weeping and nashing of teeth pre A2 forum approval when I asked about 727 carbines. In fact that is how the A2 sub section was formed. No A2s allowed. Which is I think is actually for the best but the retro side wants to have there cake and eat it too with 723/733, aka A2 carbines.
If you want to discuss the A1 aspects of your build then great even if it’s 6.8 spc. But if you want to talk about 6.8 spc it’s self I think it should be moved.

Disregard.

I would message the Mod for this forum.

Gothic Serpent & early GWOT posts used to go here: I guess I didn’t get the memo that they moved. So does this go in the A2 forum now (even though these 6.8 ARs were flat tops), or the general AR Discussions forum? Mods just LMK where it should go…

From the code of conduct post pinned at the top of the page in red….

“4) The Retro Forum was started for those members interested in discussions covering the early models of the AR15 / M16 and its related equipment. While we do not have a set rule regarding what is considered “retro”, posts involving other firearms or equipment may be moved to a more suitable discussion forum at the discretion of the Moderators or Site Staff.”


Key words “Early models of the AR15/M16”. GWOT is NOT retro.  The mods will most likely end up moving the thread to the proper forum

6.8 is not retro, that's why it got locked.

now it's here...

https://www.ar15.com/forums/ar-15/6-8-spc-Development-w-5th-SFG-and-USSOCOM-MK12-Variant-/118-785214/
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since you're confused, this is retro...

Sweet-will check out the linked thread-much obliged! (And thanks for the helpful “retro” pics, brochacho-John Plaster looks dreamy!) 🤭

I adopted 6.8 last year when PSA was running a special on uppers, now have 3 including a Daniel Defense factory 16" and an 18" barrel swapped into a DPMS.  Love the cartridge.  Bolts are easy, mags are easy, reloading is easy and it just works- plus it hits like a hammer out of short and long barrels.  1750 Ft/Lbs out of the PSA 18" was easily achieved with Hornady 110 Bthp

Since the bolts and Mags are shared with .224 Valkyrie, it leaves some nice upgrade options for your .224 stocks also.  As far as factory ammo, I think it's reasonably available and will remain so.

A new thread with the same info was opened up. It definitely brought some people out of the wood work, which was cool.

I built several 6.8 SPC uppers almost 20 years ago. I rarely shoot them.

IMO, they enable an AR-15 to become a large game hunting rifle. Deer is what I mean by large game.

Pigs too.

When push comes to shove, 6.8 and 6.5 AR's are really handicapped when ammo is tight. We have suffered several panics in the last twenty years, and the first ammo to dry up is these two.

For self-defense, give me a 5.56mm rifle and quality bullets and the rest is a done deal.

For many years my AR's have only been in 6.8 spc, I dabbled in 5.56 AR's a little, but tossed them to stay with 6.8. I just recently built another AR in 5.56 for ammo compatibility, should shtf I want at least one firearm in that caliber. Needless to say, the price of 5.56 is ridiculous, but still nearly half of what 6.8 fmj's cost.