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What to Do with the 6.8?

Years ago, against my better judgement, I had an opportunity to buy a barely used 6.8 SPC AR-15 upper for a pretty good price, so I took it. My first clue there was trouble should have been was how badly the case head was marred after extraction. I always made my reloads lighter than factory, but reality is I could only ever push about 2100ft/sec at the muzzle without creating notable symptoms of overpressure. Factory ammo all exhibited overpressure signs.

Turns out that manufacturer’s supplier of that upper over-chromed their barrels, and so they all had pretty significant chamber pressure issues. Not knowing how safe it really was to shoot, and not liking the anecdotal evidence that suggested I could only avoid overpressure symptoms at positively anemic velocities, it’s sat in my safe for years unfired.

I’ve been debating whether it makes sense to re-barrel that upper in 6.8, or just repurpose the upper for a standard 5.56x45mm AR, sell the 6.8 brass, bullets, etc, and move on. The only reason I’d even re-barrel in 6.8 is because of just a little inner gun hipster. But I don’t really know how much of a future 6.8 has, and I can’t abide by modern guns I don’t ever shoot taking up safe space.

54 Responses to “What to Do with the 6.8?”

  1. National Observer says:

    Have you ever slugged the barrel to see just how over-chromed it is? It must be a lot, because I have never found that bullets oversized for the bore only a couple thou or so ran pressures up all that much.

    (A long-gone relative who was a WWI veteran told of firing 7.92 x 57 German military ammo for “target practice” in their 1917 Enfields, in France, and German military ammo was HOT!)

    If you wanted to be a real gun hipster, maybe you could buy dies to swage up 6.5mm bullets to whatever the true groove diameter is. What could be hipper than being the only guy in town with a 6.65 SPC?

    • National Observer says:

      “I have never found that bullets oversized for the bore only a couple thou or so ran pressures up all that much.”

      I thought about things for a couple minutes, and it came back to me that the problem may be one of bore roughness, more so than bore/groove diameter.

      A friend of mine had experience with an ultra-cheap .243 Mauser ’98 barrel. The first shot would be OK, the second shot would badly crater the primer, and with the third round, the primer would just disappear. It turned out the barrel had an ultra-rough spot in it that would collect jacket metal and really run pressures up. We fire-lapped the barrel using mild loads and jacketed bullets embedded with fine lapping compound, and the rifle became well-behaved and capable of very decent accuracy.

      I know nothing about the quality of the uppers you speak of, but I have a suspicion that if the plating is known to often be out-of-spec, the quality of the barrels wasn’t that good to begin with, and bore roughness might be the real problem. It might be worthwhile to scrub the bore thoroughly with an abrasive cleaning compound, and then see if the pressure problem returns over several rounds. If it does, suspect bore roughness, and consider fire-lapping it as described, using jewelers/machinists rouge for the lapping compound. Of course, rebarreling with a quality barrel would be the surest fix.

    • Ray says:

      I would have serious stink eye at that war story, as 7.92X57 was all .323 by 1917- 1918, and the 1917 Remingtons were all considered “unserviceable” when they reached a .303 (311) boar diameter. There was a rash of self inflicted wounds and Rifle KB’s from trying that in the 1919-1920 time period that was quickly quashed by the brass. But NO you cannot fire a .323 bullet from a 308 rifle. Not if you want to keep your digits.

      • National Observer says:

        “Not if you want to keep your digits.”

        I heard that story repeated when I was a real little kid. Obviously I can’t vouch for it. When I got older and more knowledgeable, I more questioned how many .30-’06 rifles would chamber a 7.92 x 57 round at all given that the ’06 is more tapered. But, I never have gotten around to testing it, even with empty brass. Plus, with loaded rounds, you would be forcing a few millimeters of bullet-filled 7.92mm neck into a .30 cal. chamber neck. I personally have witnessed blow-ups due to forcing unturned/unreamed case necks into tight neck benchrest chambers.

        On the mitigating side, for what it’s worth, the larger capacity ’06 chamber (once the case had blown out to fill it) might tend to mitigate over-pressure.

        Back to the story itself, since I wasn’t there to question the teller, I have no idea whether it was alleged to be one guy getting away with it one round, or several soldiers firing many rounds. Regardless, I just took it as a testimony to the strength of the 1917/1914 actions.

        More to the point of the current subject, a friend once owned and loaded for a “7.65-’06”, a 7.65 ’91 Argentine Mauser rechambered to .30-’06. He loaded with .311″ – .312″ bullets. Someone later took some of that ammo and was shooting it in their standard .30-’06, and never noticed anything amiss other than that it didn’t group well at all. So, squeezing a jacketed bullet down a couple thou does not seem to run pressures up huge amount. The issue there being to call to question whether over-chroming really was the prime source of the over-pressures with the 6.8.

        This subject interests me “academically” but not “practically,” so I haven’t spent a lot of time on background. However in the little time I did spend I found one 6.8 SPC account that concluded “on the THIRD round KABOOM.” That sounded an awful lot like my story about the rough-bored .243.

  2. Bill C. says:

    Just put a fresh 6.8 barrel on it. It’s a perfect travel hunting rifle. I have one for my son for when he gets older. Lots of guys like 6.8 in other states and if this state finally lets ARs be used for deer then it’ll take off here big-time.

  3. Zundfolge says:

    Is the barrel on it an SPCII or just an SPC? If you want to shoot 6.8 you would be better off with an SPCII barrel so you can shoot any 6.8 ammo you come across.

    I think the .300 blackout has a brighter future if you want a “gun hipster” caliber.

  4. CarlosT says:

    Satisfy your gun hipster and convert it to a 300BLK. Birds, stones, etc.

  5. Ian says:

    AR15 performance barrel all day! I love mine.

    • Mike says:

      ARP and Bison Armory are the two brands I trust the most w.r.t. 6.8.

      Also, you can always convert a 6.8 to a .224 Valkyrie (but again, get the barrel from ARP).

  6. HSR47 says:

    Since it’s an SPC barrel, rather than SPCII, and you’ve had issues with it, I’d definitely recommend tossing the barrel as step 1.

    As for what barrel to replace it with, you have a number of options:

    * 6.8 SPCII: I’d recommend against this — the 6.8 SPC has significantly waned in popularity, and signs point to this trend continuing. It’s a caliber that’s chief selling point was that it sort of fits in an AR15, and that it performs better than 5.56×45 under certain circumstances; There newer options that do that better while being more popular/available. Having guns in obscure calibers can be fun sometimes, but the increased costs (both time and money) involved need to be accounted for — is all of that really worth it to you? On the whole, since PA won’t let you do much more than take it to the range, I’d say that 6.8 SPC is an overall poor choice in the current market.

    * 300 BLK: It’s relatively inexpensive, and relatively easy to load for. On the other hand, everyone’s doing it.

    * .22 Nosler: It has more capacity than a 5.56×45, but uses a rebated rim so that it can use a standard 5.56 bolt. That lets you push higher velocities, which is helpful for accuracy at longer distances. If you decide to go this route, I have a handful of cases in my pile of brass that I’d gladly pass off — We don’t live that far apart.

    * .224 Valkyrie: Similar to the .22 Nosler, but doesn’t use a rebated rim (which likely means it will have the same bolt strength issues as 6.5 Grendel, 6.8 SPC, et. al.). Allegedly it’s better designed for precision shooting than the .22 Nosler.

    TLDR: Being a gun hipster can be cool, but it can also be an expensive PITA. The ideal GH calibers are the ones that most people agree are cool, but that only actually sell in quantities barely sufficient to ensure that they stay relatively available. 10mm Auto is a perfect example of this.

  7. Sebastian says:

    Thanks for the response. I’m leaning to ditching the 6.8 entirely. I’ve never really shot it and I am concerned about putting any more money into a boutique round that’s dying off. The .224 Valkyrie is tickling my inner gun hipster. But I’ll probably go with a decent 5.56x45mm setup.

    • Switch out the barrel to the .224 Valkyrie. You can still use the old 6.8 magazines and the 6.8 bolt carrier group.

      I remember talking to a rep from Ballistic Advantage at the NRA AM who said they were dropping their .22 Nosler barrel in favor of the .224 Valkyrie. They thought it had better performance.

      I’m still keeping my 6.8 SPC II because I want a hog rifle that might also be used for deer.

    • Sigivald says:

      Do you have a pistol-caliber AR already?

      (I keep toying with the idea for the lower I have lying around waiting for a purpose, but … it’s spendy and I can’t claim I “need” a pistol-caliber carbine …)

  8. Dave says:

    it sounds like you have a bad barrel now and the real issue is caliber choice. if you finally got rid of your man bun, it may be time to say goodbye to the 6.8 as well. OTOH, if .224 V. takes off, there might be a resurgence of popularity in the 6.8 at least, but you should probably not reconsider the man bun.

    The good news is that you have lots of caliber choices available to you. You could try a .224 v barrel or upper from PSA for example pretty inexpensively and see if you like it. If you do, you can always go grab a more long range suitable barrel from Bison or whomever else is out there with a twist rate faster than 1×7.

    Note, 224v accuracy reports have been sparse and inconsistent as of yet. I haven’t seen anyone reporting repeatable and consistent results yet. maybe they’re out there, but so far I’ve seen a lot of inconsistency.

    • Sebastian says:

      Never had a man bun. The only reason I bought 6.8 is because I got the upper below cost, along with several hundred rounds of brass and two magazines.

  9. Other Steve says:

    You already know you’re going to dump it. You’re just looking for confirmation 6.8 is dead, and it is. It lost to 300blk big time.

    Unless you have a specific need for a different caliber, just make your internal supply system easier by going to 556. I see reasons for 300blk or 6.5G now .224V but you really need to know why you have it and exactly what for – otherwise you’re just being a collector… and while there is nothing “wrong” with that, we need less Collectors and more Users.

    6.8 was right after the piston-mania of 2008. Just as pointless and just as shilled on forums by Collectors who needed something “better”.

    How many hours of formal carbine instruction do you have vs number of carbines? If it’s not at least 8:1, that’s where the money should go.

    • Sebastian says:

      “You’re just looking for confirmation 6.8 is dead, and it is.”

      Pretty much. Also looking for barrel suggestions for something in 5.56.

      • Mike Q says:

        Faxon Pencil weight. Your rifle will feel like it’s floating in your hands.

      • Matt says:

        What are you looking to do? I’ve got some AR Stoner stainless barrels in .223 Wylde with 5R rifling that are awesome general purpose shooters.

        If you driving for accuracy, I highly recommend Hart barrels. They’ll turn to whatever spec you want and the quality and accuracy is excellent. I have one on a sub-MOA AR-15 platform shooting super heavy 90gr .223. I built it before .224V came out and basically my gun shoots better than the Valkyrie offerings but at the downside of being overlength for the magazine (the rifle is a single-shot).

        • Sebastian says:

          Looking more for a general purpose shooter. My club’s rifle range only goes out to 200 yards. I won’t be doing much long distance work with it. But I wouldn’t mind being able to reach out farther if I go visit somewhere with a longer range.

          • Mark says:

            To appease your inner gun hipster, you couldn’t go wrong with one of Noveske’s 6.8 stainless offerings?

          • Other Steve says:

            I’ve sucessfully used my 11.5” BCM elwf suppressed at 450y on E-sized steel. Range is nothing but a number and 11.5” will get you easy 300y before you really need to know holdovers.

    • Sebastian says:

      6.8 SPC. There was no II spec when it was manufactured. I got in around 2007. Builder was Ko-Tonics, who are not even in business anymore. No idea who was making their barrels.

      • aerodawg says:

        IIRC that bad batch of barrels is what did Ko-Tonics in. They tried to make right with the customers and just couldn’t handle it financially…

  10. Jim W says:

    It sounds you have a poor quality barrel in an obsolete chambering of a fading fad caliber. It’s been sitting for ten years with no use. Just throw it in the trash and move on. 6.8 was never a good idea. Now it’s a bad idea with rare ammo.

    I’m actually thinking of building an AR for the wife and I’m considering a pencil barrel. The only problem is that none of the available barrels are chrome lined.

    And yeah, stick with 5.56. The reasons are many and obvious. I kinda wish there was a more hunting friendly round for the AR like the old 30 RAR (that also never caught on), but the closest thing that is easily available is 300blk supersonic. Which actually isn’t terrible.

    • Mike Q says:

      Don’t get hung up on chrome lining. Chrome is A good way to finish the inside of a barrel. It’s not THE good way to finish it. Nitride has real advantages and no significant drawbacks. If you are interested in AR barrels I cannot recommend the InRangeTV Faxon Q&A videos enough, search it on Youtube it’ll come up. It’s a few hours to watch through them all but well worth it.

      • National Observer says:

        Continuing the theme I started above, I have a suspicion that sometimes chrome is used to conceal poor-quality, very rough barrels. Other techniques of concealment have been used, so I don’t see why chroming would not be, especially if it was used as a feature supposed to increase desirability.

  11. You won’t be able to get any 6.8 from the National Guard armories when President Chelsea Clinton gives Antifa badges and arrest powers!

    • Benjamin "Quirel" Warren says:

      If you are stealing ammo from a National Guard armory, it’s not much harder to steal a rifle when you are in there.

      Just saying, of all the reasons to ditch 6.8 SPC, that might not even be in the top ten.

      • Drake says:

        Old National Guardsman here – good luck getting into one of those vaults. If you do or somebody opens it for you, you’ll find plenty of rifles but possibly zero ammo.

  12. Will says:

    Talk to a plating shop. They may be able to strip out the chrome in one of the production steps of chrome plating. Might make the barrel salvageable at an affordable price.

  13. Mike says:

    For a while, there was a reamer being passed around on 68forums to be used by hand that would open up the throat to SPC II spec and remove excess chrome plating. If you could find someone with an SPC II reamer, I bet that’s all you’d probably need to salvage your current barrel.

  14. aerodawg says:

    I’m kinda in the same boat. Got a 6.8 I bought years ago for hogs and coyotes, which it has worked well for but never shot much outside that. Strongly considering shooting up my remaining 6.8 ammo and swapping the barrel to 224V for better long range coyote gun….

  15. Brad says:

    Using cost as the primary consideration, switching to 5.56mm is obviously the best choice.

    However, if you already have a 5.56mm AR and want to have an AR in a different flavor caliber you might consider the 6.5mm Grendel, because of the availability of Russian made cheap factory ammo. The 6.5mm Grendel does everything a 6.8mm SPC can do, and then some.

    Long term, I think the 6.5mm Grendel future is bright because of its inherent compatibility with 7.62x39mm firearms. For example, the 6.5mm Grendel version of the Molot Vepr. As the domestic manufacturing base for Kalashnikovs expands I expect some of those companies will offer 6.5mm Grendel versions to complement their basic 7.62x39mm versions.

  16. HL says:

    Yeah, not sure what 6.8 does the 6.5g or 300blk doesn’t…maybe cost more? Good luck with whatever you choose!

  17. Ian Kocher says:

    Lap it and all it a day.

  18. Wolfman says:

    So, the .224 Valkyrie is a curious looking machine, but it’s built much more for long-range competition than anything else. Was talking to the Savage rep, and looking at the loads and rifles we are getting in stock, and it has a very fast twist to stabilize 70-90 grain bullets, but doesn’t stabilize anything under 70 very well, and according to the guy the from Savage, doesn’t really shoot 60 or under at all. The weight difference largely eats the increased case capacity, so the VLD bullets start slower than 55 gr ball, but pass that round about 400 yards out, and shoot about 2′ flatter at 600 yards. Its a neat round, but doesn’t fit much that I’m doing at present.

    I still think that the .30 Remington case would be neat left full size and necked down to .22 caliber, but it doesn’t really fit any current action sizes, auto or otherwise. I’d consider building one for a long range varminter, splitting the difference between the .223 and the .22-250. That doesn’t help you here, at all, though.

  19. National Observer says:

    “I still think that the .30 Remington case would be neat left full size and necked down to .22 caliber”

    Ballisticly speaking, it was done decades ago, arguably with any of the .22/.30-30 wildcats, or for that matter, the .225 Winchester. The point of all the sexy “gun hipster” calibers being discussed here is to fit the AR platform for various purposes.

    • National Observer says:

      Just being a PITA, but, on the “done decades ago” theme, it occurred to me that to the extent that the .219 Donaldson Wasp was a “standardized wildcat”, it in turn was “wildcatted” to other calibers, possibly by Harvey Donaldson himself, but more likely by P.O. Ackley, who was known for necking down/up almost every cartridge to some other caliber.

      Given that the Wasp was only about a millimeter longer than the 6.8 SPC, if anyone ever created a “.270 Wasp” they effectively created the 6.8 SPC, with the Wasp’s rim being the only difference. That would probably have been in the 1940s or 1950s when the .270 caliber was at its peak popularity.

      Speaking of “platforms,” the Wasp rim was often turned to .470″ to fit Mauser and Springfield based benchrest actions.

      Just on the theme that, “gun hipsters” notwithstanding, there is seldom anything really new under the sun in the gun world.

      • Sebastian says:

        Gun hipster is just a joke. A stand in for people who like this kind of obscure stuff for its own sake. I have to admit to being attracted to the idea of re-barreling in .224 Valkyrie. But I don’t think I’d ever shoot at those ranges enough to justify it. At least that’s what I need to keep telling myself.

      • Sebastian says:

        And yes, nothing is really new. The same fads seem to come and go, with just a different twist.

        • Andy B. says:

          On the subject of “old but similar cartridges” you may have heard of the “.22 Marciante Blue Streak,” because the Marciante brothers belonged to our club, and the cartridge’s inventor was their father, who was a very famous gunsmith back in the 1930s and 1940s.

          The “Blue Streak” was based on the .30/30/.219 Zipper/.22 Savage Hi-Power case, and was one of the earliest claimants to achieving 4000 fps — though that seems doubtful except possibly with 40 gr. bullets. But, its similarity is that it was a .22 wildcat with a casehead diameter of about .420 and therefor about the same case capacity.

          Another commercial cartridge come to think of it was the .224 Weatherby, with about the same base diameter, but belted. I seem to remember “Shooting Times” doing an article where they wildcatted it to every possible caliber including .270.

          • Sebastian says:

            Looks like there are some pictures of him. Along with a story: “Everyone seams to think it was Al that named it, but it was grandma who named the cartridge the ‘Blue Streak.’ She would often accompany her husband Al to the range. While she was sitting and crocheting she noticed the vapor trail and pointed it out to her husband.”

            • Andy B. says:

              I just found that and similar sites moments ago.

              I had guessed where the “Blue Streak” came from, and it gave credibility to the 4000 fps claim. I’ve heard that early .220 Swift loads would do the same thing. It was lead melting off the noses of the bullets. I think Winchester changed their bullets for the Swift to have less exposed lead. That may have been at the same time they reduced their weight to 48 grs., to achieve a true 4000 fps.

              I don’t know if anyone has ever identified the boundary velocity at which exposed lead bullet tips will melt. I personally have seen targets with “comet tails” of vaporizing lead spiraling out from the bullet holes, but I have never observed the “blue streaks” myself.

              Thinking like the engineer I once was, carrying the copper jacket further up the tip would not only expose less lead, but would also serve to better conduct the heat away, copper being a better heat conductor than lead. Historically (and digressing) some of our earliest nose tips for our nuclear missile reentry vehicles employed copper for that purpose, before the nosetip problem was adequately solved by carbon fiber materials.

        • Wolfman says:

          @ Nat Ob- Considering the .30 Remington is LITERALLY a rimless .30-30WCF, down to using the same load data, yes- if someone built a rimless .22-30, they would have already done it. Still doesn’t mean it wouldn’t be neat. And I did realize the point was AR platform calibers, hence the ‘that doesn’t help here…’ line.

          @Sebastian- The best is when Remington’s .244 didn’t sell very well, so they put a new spin on it and called it the 6mm Rem.

          • Andy B. says:

            “when Remington’s .244 didn’t sell very well, so they put a new spin on it and called it the 6mm Rem.”

            But they also changed the twist of the rifling from 12″ to 10″ to stabilize 100+ gr. bullets, and they needed something to brand that.

            Very coincidentally: As I sit here I can glance to my left and see the receipt for when I had a Mauser action rebarreled to .244, dated March 12, 1964. By Douglas, with a XX barrel, bottom line $42.02. But, I was bringing home $49.43 a week in those days.

  20. Kevin Crystal says:

    The reports of 6.8’s demise have been greatly exaggerated.
    http://www.gunbot.net/ammo/rifle/68spc/
    I like my 6.8, it’s taken plenty of hogs and should do fine on deer.
    If it was me I’d debarred the gun with a new 6.8 from Bison.

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