Help Ar 15 short stroking !

[Superdave831]

Yeah thunder tactical/thunderguns , well I had them laying around from the Beowulf upper i have , my buddy gave me the H buffer when I was having problems with it till I bought an h2 and wala it worked

[ScottsBad]

Don't start scaring me ,I already had this type of situation going on with my .50 Beowulf but got it fixed with the help of this forum , ok well it's a brand new upper I bought it from thunderguns , I tried A h2 buffer and A H buffer with no luck , what I meant from short stroke is when I fire it ejects but won't come back all the way back to cycle the next round , I tried the single shot to see if it stays locked and it does not , i tried the bolt carrier ring flat surface test and they are good , I do see a little carbon escape from the front sight gas block , the hex screws are on tight

Not locking back right?

There is some possibility that the gas block is not properly aligned with the gas port on the barrel. You don't see anything wrong with the gas tube, right?

[Superdave831]

Yes correct not locking back , it looks fine , that's what I was thinking that could be wrong alignment

[ScottsBad]

The BCG slides freely inside the upper receiver, right? The bolt locks and unlocks smoothly? The gas key is on tight?

Is this the only AR you have? IF not try swapping BCGs.

[ScottsBad]

Yes correct not locking back , it looks fine , that's what I was thinking that could be wrong alignment

Did you install the gas block or was it done by Thunderguns? And was the barrel dimpled for the set screws?

[Superdave831]

Yes it slides freely and smoothly, has key is on tight , only Ar I have , yeah the gas block was installed by thunder guns and it is dimpled on the set screws

[Superdave831]

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[Superdave831]

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[Superdave831]

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[ScottsBad]

Yes it slides freely and smoothly, has key is on tight , only Ar I have , yeah the gas block was installed by thunder guns and it is dimpled on the set screws

I don't mean to be rude, but do you know what the gas block is? I can't know what level of knowledge you have. The gas block (GB) in on the barrel, right? Did Thunderguns (TG) actually dimple the barrel and then you installed the gas block? OR was the GB and gas tube already installed?

So far it sounds like there is insufficient gas to drive the bolt against the buffer/spring. And since the BCG slides smoothly, is not getting hung up, and gas rings appear to be fine, I'm leaning toward a misalignment of the gas block on the barrel potentially blocking some of the gas pressure needed to cycle the weapon.

In any case I have to shut down for the night. If you get a chance to test it again tomorrow morning; Put the H buffer in it instead of the H2, lube the BCG, and try different ammo.

If you have the tools and knowledge you could check the alignment of the GB to the gas port on the barrel.