6.8 SPC II Questions for AR Guys:

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gbw

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For you AR experts:

I'm been intrigued by the 6.8 SPC II as a slightlyt better mouse trap for traditional sized ARs. So I'm thinking of converting one of my unused ARs to 6.8 SPC II.

PSA has lightweight 18" stainless barrels which seems exactly what I'm looking for, for $259, and they also sell bolts.

Is there anything else needed to do this conversion? Buffer and/or spring, etc.? I know about the 6.8 specific magazines and I'd include them.

Somewhere along the line I'd probably just create a complete rifle or at least an upper, but not 'til I know I like the result.

Thanks,
 
No, you are correct. Barrel, bolt, and mags are the only things needed for the change. It is possible that you could tune the spring and buffer for BETTER performance, but it shouldn't be necessary.
 
Go to the 6.8 SPC forums https://68forums.com/ and they can steer you right. A lot fewer options on barrels and bolts than there was a few years ago as the 6.5 Grendel became the new "IT" cartridge. However, factory ammo is available, you can use the same bolt for the newest AR hot cartridge, the Valkyrie, and Starline makes the brass for it. Quite a few hunters still swear by the 6.8 SPC though and it is an excellent cartridge for short barrel rifles (course you have to get the stamp, etc.)
 
I love my 6.8. It’s the most accurate gun I own now. It hits about like a 30-30 but shoots a bit flatter and uses better bullets. Barrel, bolt, and mags are the only things you need. As others have said, for that money you can likely do better. Look around for a used doublestar upper. Mine is a 22” heavy stainless behemoth but even so it’s a ridiculously accurate and is a shootable gun for any position. Before I let my range membership expire, I was using that gun to ring steel at 500 VERY consistently. Mags are the biggest drawback, but I suspect that with the Valkyrie being popular that mags are now going to be easier to find (assuming they interchange, and they should since 6.8 is parent case to Valkyrie).

If you don’t reload, you might want to skip 6.8 and go to the more popular 6.5.
 
Thanks, gentlemen. Id do reload, rifle and pistol, the old Dillon has passed 250,000.

I've had good success from PSA barrels, I did have one 5.56 upper that would not shoot and they took it back no questions. I'd have no problem using them again.

The attraction of PSA's barrel is it's light weight and 18" length, which fits with the lightweight rifle I have in mind. Wilson has a Lt. Wt. barrel too for about the same price, but it's 16" and I don't know if that makes enough of a difference to matter or not. Perhaps better odds of high accuracy with Wilson, but the PSA-10 that has their heavy stainless .308 barrel shoots very well. But it's heavy.

So, do those extra 2" matter in this caliber?

Thanks again,
 
I have three 6.8’s currently, a Mini-6.8, an 18” midlength AR, and a 10.5” pistol length SBR. Can’t recall the last time the Ruger saw the light of day. Both of my AR’s are Black Hole Weaponry barrels, running H2 buffers, full auto BCG’s, and JP AGB’s. The extra mass is nice to slow down the recoil impulse of the heavier bullet 6.8, and the AGB’s give ultimate control over action tuning to match my loads.

There are really only two downsides of the 6.8 SPC when compared to the 6.5 Grendel: 1) Most importantly, there’s way more market support for the 6.5, and more than likely, there will continue to be for the eternal future. 2) Magazine length restrictions and the long SPC case length mean we can’t load the really long, high BC bullets to stretch the legs of the cartridge. The 6.8 can reach way out there, but the 6.5 has a distinct advantage here. I was a died-in-the-wool 6.8er in the early days,

I have had 16”, 20”, and 22” 6.8’s in the past, I picked up my 18” barrel just to grab a little extra muzzle balance, without as much length for my hunting rifle. There’s a lot of hype and nonsense about “optimized for short barrels, blah blah blah,” but the big case does hold enough powder to have considerable blast even in a 22” tube, and does pick up more and more speed as the barrel length increases. It does perform well in short barrels, but it also does perform better in longer tubes. I built my 18” based on rifle weight, length, and balance, sacrificing some speed. It’s a hammer on coyotes out to 600, which is as far as I have made an opportunity on them so far with this rifle.

Mag, bolt, barrel, and it can be any other AR compatible cartridge within an hour.
 
I actually have the same desire, I PM'ed a internet friend of mine on another forum that has built I think 3 6.8SPC AR's for himself... his answer was quite illuminating, I'm posting here for your consideration...

I really like 18" barrels for my AR's.
Have three in 6.8.
One Black Hole Weaponry, which is a 6.8 SPC II camber.
And two AR15 Performance with the 6.8 ARP chamber.
The ARP chambers are like a .223 Wylde chamber is for 223/5.56.
It has to do the Freebore length and Leade.
Any commercial 6.8 SPC ammo will fit a 6.8 ARP chamber.
What the ARP chamber does is allow for hotter loads.

Unfortunately Commercial loading for 6.8 SPC is rated at 6.8 SPC 1 pressure.
So reloading gives the best efficiency for this caliber.
Have to thank Remington for screwing up another cartridge caliber.
It is the only SAMMI cartridge where the cartridge measurements are greater than the chamber.

Checked ARP's website. Looks like they are out of the two 18" midweight barrels.
ARP has a Vendors section on the 6.8Forum.
He gives barrel updates on whats coming available.

As to what you will need...
Besides the barrel, a 6.8spc or 224 Valkyrie bolt and 6.8 SPC magazines.
Like what you mentioned. Magpul makes 6.8 SPC magazines that only fit LWRCI or a company called Sulzer Firearms. Either one you will need the matching upper and lower.
To be honest, I like the ASC 6.5 Grendel S.S. magazines. They can be loaded longer than aluminum 6.8 or 6.5 magazines. 2.300".
I picked up some Barrett 30 round 6.8 magazines. They work fine. But can only be loaded to 2.260"

For the AR-15 platform, 6.8 SPC is a great hunting caliber.
If your looking to punch paper at ranges over 300 yards, 6.5 Grendel may be a better choice.
Personally, I really like the 6.8 SPC and wildcats based off the cartridge.
Just ordered a TAC 6 barrel and dies from ARP last week.
So I have my work cut out for me figuring this one out.

I wasn't aware of the nuttiness between 6.8 chamberings, I'll have to research it more and sort it out. It looks like 16-18" barrels are the hot setup, from what I've read elsewhere, the 6.8 round gains little from any additional barrel length. I also need to research the validity of the ARP chamber. I also had a question about magazines... it seems like the camp is split between those that have zero problems, and those that can't seem to find anything that works.

I still want to build one, using my existing lower, so I'll need to do some more thinking...
 
someguy2800 said:
If you have $260 to spend on a barrel you can probably do better than PSA, but I guess I have not shopped for a 6.8 barrel.
Click to expand...

My thoughts as well, the 6.8 I owned was an 18" PSA upper and it worked fine, but if I was going to spend $260 on a lightweight 6.8 barrel, I'd probably get one of these:

https://ar15performance.com/inc/sdetail/38010/43897

Anything I would do with a 6.8 could be done just as well with a 16" barrel as with my old 18", plus a setup like that would beg for a can, where shorter is better.

They also have bolts in stock, so for $269 you'd be set.

https://ar15performance.com/inc/sdetail/3255/58452
 
gbw said:
For you AR experts:

I'm been intrigued by the 6.8 SPC II as a slightlyt better mouse trap for traditional sized ARs. So I'm thinking of converting one of my unused ARs to 6.8 SPC II.

PSA has lightweight 18" stainless barrels which seems exactly what I'm looking for, for $259, and they also sell bolts.

Is there anything else needed to do this conversion? Buffer and/or spring, etc.? I know about the 6.8 specific magazines and I'd include them.

Somewhere along the line I'd probably just create a complete rifle or at least an upper, but not 'til I know I like the result.

Thanks,
Click to expand...
After that younjust need 6.8 mags
 
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