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Thread: 6.8 SPC Pistol

  1. #1
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    6.8 SPC Pistol

    Finally got my 6.8 together. I kinda had to wing it with no 6.8 specific tools. A rag around an AR15 mag block sufficed and an MI upper receiver rod worked also somehow. The only reason I did this build is that Sulzer Firearms came out with a resonably priced lower that uses 6.8 pmags originally developed for the unreasonably priced LWRC guns.

    Does anyone have experience running an A5 buffer system with this caliber? I have an ARP 12.5” mid-gas barrel with a SLR AGB and will mostly shoot suppresed. I’m starting with a Springco green spring and A3 buffer with an A4 along to compare.

    I’m happy with the looks. My first cerakoted AR. The 2.5-12 Accupoint is just to check accuracy. Probably a 3 to 5 power later.

    Ignore the curly brace.





    “ When I comes to modern politics, I think the inverse of Hanlon's Razor applies...In other words, "Never attribute to stupidity that which is adequately explained by malice." - Kerplode

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    ARP says he ports his barrels for a carbine buffer. I have mine recently built with an A5 but haven’t tested it yet.

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    Looks great. I have the same barrel but haven't put many rounds through it yet nor worked up a load. I think an ACOG is about perfect for that. The gray looks great, too. I just use standard lower with Barrett mags, but if you handload you should be able to eek out some better and great performance from the round with the extra COAL. Mine is a standard buffer but I can see the A5 softening the recoil a bit. Although, I suspect a JP SCS would be even more noticeable.

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    Nice looking pistola..

    I’d be in for the 6.8 , if more cheap plinkin ammo was available..good little round though.

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    UPDATE

    After several frustrating range trips I hope I have solved my issues with the 6.8. An A5 H2 and lots of AGP adjusting finally got the bolt to hold on last round both with and without suppressor. But the fired case would not eject. I had to pry each one off the bolt face manually. Much research indicated several possible causes - debris under the extractor; defective extractor claw, machining defect on bolt face, weak extractor spring, and under-gassed.

    The last I pretty much unscientifically discounted from the get go. Even with mid-gas this has more recoil and gas in the face than my canned blowback 9mm and .308 ARs. And I trust ARP got the gas port right.
    The claw and bolt face were pristine and zero chunks in with the extractor. Today I replaced the spring with the Sprinco recommended 4 coil which fetlt stiffer than the stock ARP. So that may be the cure. I did find a machining defect in the extractor pin hole. Unlike every other bolt I have torn down this was like trying to knock a bolt catch pin out. Major pounding. One hole side had a ridge halfway inside that reduced the inside diameter. Not wanting to risk opening the hole too much I just reamed with a square file handle until the pin went in still tight, but with less binding. Though I doubt that would restrict extractor movement. But possible.

    Manually pulling the charging handle now pops the round out which it did not before so fingers crossed. Range time next week weather permitting.
    “ When I comes to modern politics, I think the inverse of Hanlon's Razor applies...In other words, "Never attribute to stupidity that which is adequately explained by malice." - Kerplode

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    Sprinco comes through. No malfs on a short range trip yesterday.
    “ When I comes to modern politics, I think the inverse of Hanlon's Razor applies...In other words, "Never attribute to stupidity that which is adequately explained by malice." - Kerplode

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    Quote Originally Posted by Uffdaphil View Post
    Sprinco comes through. No malfs on a short range trip yesterday.
    Nice. So, if I understand correctly, you replace the extractor spring and worked the extractor pin hole so eliminate any possible binding and that solved the problem? Glad you got it worked out.

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    Yes. Fortunately Sprinco specifically addressed my ARP bolt-

    “Enhanced 4-Coil springs maintains the load of a NEW Mil-Spec Spring and is recommended for use in 18" +BBL lengths for those who retrieve their brass for reloading. While the 5-Coil XP spring is totally reliable for all 5.56 BBL lengths, it can be aggressive on case rims on longer length BBLS and may be too strong for some bolts with extremely tight bolt face tolerances (E.G. AR Performance 6.8 SPC precision machined bolts.)”

    The 18”+ BBL length made me wonder, but it works.
    “ When I comes to modern politics, I think the inverse of Hanlon's Razor applies...In other words, "Never attribute to stupidity that which is adequately explained by malice." - Kerplode

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    It's kind of funny when people come out with aftermarket accessories to enhance aftermarket accessories.

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    Quote Originally Posted by BoilerUp View Post
    It's kind of funny when people come out with aftermarket accessories to enhance aftermarket accessories.
    I think you just defined weapon evolution.

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