Feeding and lockback issue with new rifle w/pics... The diagnosis?
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  1. #1

    Default Feeding and lockback issue with new rifle w/pics... The diagnosis?

    So I just finished my first 6.8 rifle and took it to the range to sight in the scope and immediately noticed a problem. On the last round, the Bolt wouldn't lock fully to the back(and once or twice it didn't lock back at all), requiring me to use the charging handle on each subsequent mag change. It would eject every round fired, but every once in a while I would get a FTF.

    It was well lubed and the action is very smooth. I did try 2 different ASC 10rd mags and 2 different weights of bullets(Older SSA 90gr and SSA 110gr)

    Is it under gassed? Overgassed or cycling too quickly(14.7 welded, with mid-length gas and CAR buffer)?

    Is it clear to anyone what the problem is?
    image1sm.jpgimage2sm.jpg
    Last edited by Gytheran; 03-05-2017 at 04:36 PM.

  2. #2
    6.8 SPC Lover
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    Default

    Will the bolt lock all the way back on a empty mag when you manual cycle the action?

    Have you checked alignment at the gas block and barrel?

  3. #3

    Default

    Quote Originally Posted by cag215 View Post
    Will the bolt lock all the way back on a empty mag when you manual cycle the action?

    Have you checked alignment at the gas block and barrel?
    The bolt locks back manually just fine.

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  5. #4
    6.8 SPC Lover
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    Quote Originally Posted by Gytheran View Post
    The bolt locks back manually just fine.
    This is THE most frequent malfunction discussed on this site. usually something simple,, but the experts will need more information. what buffer is being used? carbine type? is it marked H for heavy? What BCG is being used? M16 or lighter versions? is this the only ammo you've shot through it? is the gun a new build? what bolt is being used? all these things by themselves may not be a problem but when coupled together could cause issues. gas block alignment is usually the first thing that should be checked.
    Some day your life will flash before your eyes, do something worth watching.

  6. #5
    6.8 SPC Lover
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    As the others have alluded to, you are most likely slightly under-gassed which can be due to multiple causes. The whole system is setup to balance the generation/capture of the gas (ammunition, barrel, gas block & tube) with the management of the forces created by the gas (BCG, buffer, buffer spring).

    On the FTF, I suspect the feed angle of the magazine is too shallow, but that's only a hunch.

  7. #6
    New to the 6.8
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    Default Same here

    [QUOTE=Gytheran;1010506]So I just finished my first 6.8 rifle and took it to the range to sight in the scope and immediately noticed......


    I am in the same boat. I have run about 100 rounds through mine and am having the same issues. Will not lock back after last round except for every once in a while. It fails to feed from time to time. Some times it will feed the next round into the chamber but it never resets the hammer, therefore I have to manually eject the loaded round and grab another. I have ARP 16" with match set Anderson receivers and AIM Surplus BCG and bolt and mid length gas tube and carbine buffer and spring. ASC Magazines; 4 different ones. I'm thinking it is just stiff and needs using but I can't be sure.

  8. #7

    Default

    Quote Originally Posted by moboy56 View Post
    This is THE most frequent malfunction discussed on this site. usually something simple,, but the experts will need more information. what buffer is being used? carbine type? is it marked H for heavy? What BCG is being used? M16 or lighter versions? is this the only ammo you've shot through it? is the gun a new build? what bolt is being used? all these things by themselves may not be a problem but when coupled together could cause issues. gas block alignment is usually the first thing that should be checked.
    Thank you for the reply. New rifle, only SSA 90 and 110gr was shot though it, Carbine buffer, mid-length gas, Bolt and FA carrier from PSA(came with the 6.8 upper).

  9. #8
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    Did you assemble the upper?

    Check your gas system by making sure the gas block is perfectly aligned with the gas port in the barrel. Also make sure the gas tube port is aligned and clear with the port in the gas block.
    It sounds like your slightly under gassed which may be a mis-alignment or blockage within your gas system.

  10. #9

    Join Date
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    Default

    constructor has a great short stroking write up in the ar15 performance forum . I had some problems with 110 ssa not cycling my rifle. they had some low powered ammo for a while, there's a thread on it here somewhere.

  11. #10

    Default

    Quote Originally Posted by semi_cop View Post
    Did you assemble the upper?

    Check your gas system by making sure the gas block is perfectly aligned with the gas port in the barrel. Also make sure the gas tube port is aligned and clear with the port in the gas block.
    It sounds like your slightly under gassed which may be a mis-alignment or blockage within your gas system.

    Nope. I bought a complete upper and lower in two purchases and simply slapped them together.


 

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