Questions On The 6.8 SPC
BY Herschel Smith
3 years, 6 months ago
Here are some interesting articles on the 6.8 SPC: [1] (in which our own Georgiaboy61 figures prominently in the comments), [2], [3], [4], [5], [6], and [7].
Points. Some discussions focus on the 6.8 SPC and 6.8 SPC II, stating that most rifles released today chambered for this round are for the 6.8 SPC II, even though that’s not the SAAMI spec round.
Next, it’s my understanding that a 6.8 SPC upper receiver can be coupled with any milspec AR-15 lower receiver.
Finally, within 100 – 200 yards, it appears to be fairly well established that this is a fine round for whitetail deer (perhaps not mule deer).
Comments and observations on this round, and/or any of the points above? It seems that this would be a fine option for deer hunting without purchase of a new complete rifle.
On June 11, 2021 at 2:49 am, Chris said:
“6.8 SPC upper receiver can be coupled with any milspec AR-15 lower receiver.”
I have a Original 6.8 Shorty Piston type (10yrs old anyway-brand not important) and that upper runs like a purring kitten, it just runs, on my LEGALY(for you atf) owned SF Lower.
Suppressed is even better.
Mags-mix of 556 and Barrett. No Issues as of now.
Ammo-whatever brass cased u.s. made 115otm’s i can find.
I am speaking from a …moderate round count here.
Real Life CQB. It aint gonna be protracted if your enemy has any skills.
Pleasent to run might i add.
I bought it and also built a 16” that is SPEC II
For what appear to be the correct reasons.
CQB out to 300-400 max.
The 16” has a Pricey bolt, carrier and barrel. That upper and lower are a “Matched Set” says the company. They are tight!
Glass is 1-4pwr MIL reticule vortex.
The thing is a .3 to .4mil gun allday at 100.(roughly a inch to a inch plus)
Even after running it allday at a a training facility.
I always start with zeroing (5rds) and end with zeroing(5rds) at the end of a “Paying” training day. Lets me, understand the weapon and it’s ballistics.
Point here is filth, copper and accuracy.
They run you harder and longer than you do yourself at home(if your that lucky) or the “sand pit” (public ranges, round us anyway dont want …hoppin poppin and communicating)
Thats the only thing (i) can factually say.
Perhaps I just got lucky. Even though luck has never really been my buddy. Haha.
I can not speak to hunting, i just dont. Lazy.
And hope to NEVER have to speak to 2 legged rabid animals type.
Buuuut, I’m pert sure…
for the purpose I got it..
It’ll do what I need within those parameters.
Ammo..has never been super plentifull (i have quite abit of Original SSA 115otm’s,) and its real tough right now.
If you didnt have a stash before, i doubt very few ever will for sustained use.
Had I NOT already been …vested
i dont think i ever would pick it as a First gun or primary.
All i got
On June 11, 2021 at 11:44 pm, The Wretched Dog said:
Shorter answer: “It seems that this would be a fine option for deer hunting without purchase of a new complete rifle.” – Yes; the only drawback is you need purpose designed magazines. Due to the larger case diameter, 6.8SPC do not stack properly in 5.56 magazines.
So you need an upper, and a few 6.8SPC (or 6.5 Grendel) magazines.
Longer answer: In reference to the first article:
“It is very curious to me that a round that was designed with an accurized designated marksman’s rifle in mind also features such a short ogive and low muzzle velocity. Typically, medium/long range precision weapons platforms place a premium on both the ballistic coefficient and velocity of the projectile, seeking to obtain as laser-like a trajectory and as high a retention of energy as possible. The 6.8mm SPC runs directly counter to this.”
The 6.8 SPC was not, repeat not, originally designed for the designated marksman role, that is – medium/long-range precision; it was designed to provide significantly improved terminal performance in direct combat out of 14.5-inch M4 barrels. Its significant design configuration was intended to obtain all of the cartridge’s potential velocity in 14.5 inches of barrel, with twice the mass of the 5.56mm. To drop opponents in their tracks at the short ranges where green-tip zipped right through.
Despite Remington’s problems with the original cartridge development/performance, the 6.8 SPC II achieves its design purpose, and is an excellent intermediate caliber choice for an AR-15 platform. (The current Army initiative to field a future 6.8mm cartridge is a different program; with different purposes.)
I don’t hunt. If I did, I would choose my 6.8 over a 5.56 any and every day. Son no. 2 has a 6.5 Grendel. We argue which is better. I’ll give him the edge for longer shots due to ballistic efficiency, but at practical (less than 400 yard) ranges, there isn’t much difference.
However, Alexander Arms 6.5 Grendel magazines are very superior to the 6.8SPC mags I have. The cartridge diameters are close enough that either cartridge works in either magazine. Sadly, neither the 6.8 SPC, nor the 6.5 Grendel are compatible with the standard 5.56 mag – the ribs are shallower (you can load about 8 to 10 rounds before the 5.56 magazine bulges such that it won’t clear the magazine well. I do not know whether the 6.8SPC chambers reliably using a down-loaded 5.56 mag; I haven’t tried that.)
So, yes, I like my 6.8SPC very much, especially with an 18-inch barrel (rather than the standard 16-inch civilian barrel). But, with the standard commercial loads, I doubt I am getting any velocity bump with the longer barrel; I just like the way the 18-inch length handles.
TWD
On June 11, 2021 at 11:47 pm, The Wretched Dog said:
I might add: go check out Bison Armory for very fine 6.8 barrels or uppers (when they can keep up with demand). Also .224 Valkyrie.
Note: I have no financial interest in Bison Armory. I am just a satisfied customer.
TWD
On June 12, 2021 at 9:58 am, Ned said:
LWRCI makes 6.8 dedicated receivers and full rifles that work better than standard 5.56 lowers. https://www.lwrci.com/SIX8-A5-Razorback-II_p_264.html
On June 12, 2021 at 9:38 pm, The Wretched Dog said:
Ned: Define “work better with standard 5.56 lowers.” I do not understand what the purported issue is with mating a 6.8 SPC upper to an AR-15 lower – they are compatible.
My first 6.8SPC was a 16-inch barreled upper that I swapped onto my DPMS AR-15 lower. Recently, I replaced the 16-in 6.8SPC upper with one from Bison Armory with an 18-inch barrel – merely because I prefer the 18-in configuration (my 5.56 rifle also has an 18-in barrel).
Both uppers mate flawlessly to, and function flawlessly with, a ‘standard’ AR-15 lower.
TWD
On June 12, 2021 at 10:04 pm, Brad said:
I’m thinking just go with 300 ACC and quit wasting your time.
On June 14, 2021 at 8:19 am, Ned said:
Wretched Dog: Should have said work better with the oversize 6.8 Magpul mags they were designed specifically to use.