Barrel Accuracy issues
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  1. #1

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    Default Barrel Accuracy issues

    I bought a 18" 6.8 barrel and can not get it to shoot as advertised. I have tried 95 gr ttsx 110 gr vmax and 120 gr sst. I have tried H322 and AA2200 doing optimum charge weight load development with each powder with each bullet. I played with seating depth from 2.260-2.295 in .005" increments. I have also used 2 scopes to rule out scope issues too. I took the muzzle break off and shot it without. I also looked at the crown using a magnifying glass. The gun is gassed right as the brass is landing at 3-4 o'clock. I even bought some factory hornady ammo just to see what kind of difference it made and I was getting 3" groups using that. I have put close to 200 rounds through this barrel trying to get it to shoot something half way decent. The best group I got was 120 gr sst over 27.2 gr of 2200 with OAL of 2.285" and that was a little over 1.5" group. I shoot off sandbags to ensure the best rest I can. I have several other ar's not in 6.8 and all of them will shoot under MOA with a couple of them shooting 1/2 MOA. Also, trigger is a crisp 2lb trigger. I have been working with the manufacture with this issue and they are very helpful and easy to deal with, I'm just trying to figure out what it could be as I've built a bunch of ar's using several different barrel makers and have never had this hard of a time trying to get a barrel to shoot that was guaranteed match grade accuracy. As of right now I sent my complete upper to the manufacture for them to do some testing on it. Just curious if anybody else has had this problem and was it a bad barrel that needed replacing?

  2. #2

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    Default

    ​Also, the barrel is 1:11 twist unfluted

  3. #3
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    Default

    Did the barrel maker give any guarantee or expectations of the accuracy you could expect? Have you contacted them?
    01 FFL, NRA, GOA, NAGR
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  5. #4
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    Quote Originally Posted by Woodstock View Post
    Did the barrel maker give any guarantee or expectations of the accuracy you could expect? Have you contacted them?
    He said he sent complete upper to barrel mfg.
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  6. #5

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    Match grade accuracy and 100 percent satisfaction guaranteed. I have no doubt they will take care of it just trying to figure out why it will not shoot.

  7. #6
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    Quote Originally Posted by Destry View Post
    Match grade accuracy and 100 percent satisfaction guaranteed. I have no doubt they will take care of it just trying to figure out why it will not shoot.
    I guess i missed that in the original post. The only time I have run into that was with a gas block that was a little too tight a fit inside the hand guard so it would hit when the barrel whipped. Hopefully they will figure it out.
    01 FFL, NRA, GOA, NAGR
    "This nation will remain the land of the free only so long as it is the home of the brave."
    ~Elmer Davis

  8. #7
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    have you tried a good copper cleaner in the barrel? maybe you have copper fouling?

    LUCK
    is the residue leftover when you subtract chance from preparation.



    If you reload, turn a flat based bullet around and seat it backwards in the case with apx .170 of the full dia part of the bullet left outside the case. Chamber it. If it chambers you have a SPCII. If not start seating the bullet deeper. If the full diameter part of the bullets ends up apx .070 out it is a SAAMI chamber.

  9. #8
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    Quote Originally Posted by Destry View Post
    I bought a 18" 6.8 barrel and can not get it to shoot as advertised. I have tried 95 gr ttsx 110 gr vmax and 120 gr sst. I have tried H322 and AA2200 doing optimum charge weight load development with each powder with each bullet. I played with seating depth from 2.260-2.295 in .005" increments. I have also used 2 scopes to rule out scope issues too. I took the muzzle break off and shot it without. I also looked at the crown using a magnifying glass. The gun is gassed right as the brass is landing at 3-4 o'clock. I even bought some factory hornady ammo just to see what kind of difference it made and I was getting 3" groups using that. I have put close to 200 rounds through this barrel trying to get it to shoot something half way decent. The best group I got was 120 gr sst over 27.2 gr of 2200 with OAL of 2.285" and that was a little over 1.5" group. I shoot off sandbags to ensure the best rest I can. I have several other ar's not in 6.8 and all of them will shoot under MOA with a couple of them shooting 1/2 MOA. Also, trigger is a crisp 2lb trigger. I have been working with the manufacture with this issue and they are very helpful and easy to deal with, I'm just trying to figure out what it could be as I've built a bunch of ar's using several different barrel makers and have never had this hard of a time trying to get a barrel to shoot that was guaranteed match grade accuracy. As of right now I sent my complete upper to the manufacture for them to do some testing on it. Just curious if anybody else has had this problem and was it a bad barrel that needed replacing?
    Some times it's nothing more than a false reading on the torque wrench when the barrel nut seizes on the receiver. If the barrel nut ever squeaks when installing stop right there and grease it up. I take the upper completely apart and rebuild and it shoots fine second time around. Crowns should be inspected with a 10-20X loop, all it takes is one little burr on the side of 1 land.
    AR Performance 6.8 SPC, 5.56 & Grendel barrels.


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  10. #9
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    Exclamation

    A friend of mine bought an expensive high end barrel, installed, it, put on the muzzle device and found that after the first few Sub MOA shots it started shot gunning at 2-3 MOA with 4MOA flyers. He checked "everthing" including checking barrel torque twice and bedding the extention on the third time around. Then he called me and I asked if he'd pulled the muzzle device and checked the muzzle and crown. He hadn't. We checked and using a lope, as Constructor has suggested here, found a small chip was missing from one land right at the end of the muzzle. It doesn't take much and it was very hard to see, being we're both old and blind, eith the naked eye. Brownells replaced the barrel and accuracy returned to sub MOA immediately.

  11. #10

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    Good news, I talked with the manufacture today and the person I talked to said that they replaced my barrel due to accuracy reasons but he didn't know what the reason was as they just shot it and seen that it wouldn't shoot and decided to replace it. Even better news is they test fired the new barrel to ensure accuracy and he said the 2 test targets were 3 shot groups with one being less than 1/2" using 110 gr bthp. So I feel confident I can find a load it likes using my preferred 120gr SST!


 

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