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AR15.COM
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3/16/2016 9:33:05 PM EDT
I recently built my first ar15, And I am running into problem with the gun short stroking I have checked the gas block for leaks and the bolt carrier group for leaks as well the buffer tule is in spec so I don't know what it could be it will sometime shot 1 round then it will stop and I have to charge it again and sometimes it will shoot 7 then stop and I have to charge it again it will sometimes on the last round lock to the rear and sometimes it won't any idea of what I should check or do
3/16/2016 9:49:03 PM EDT
[#1]
What kind of ammo?  Does it do this with several types of ammo?  Some ammo can be underpowered for some guns...causing this problem.  It may just be an ammo problem.



What kind of buffer?






Has it always done this?  How many round fired total out of the gun?







Can you tell us more about your rifle?  Since you built it...what kind of parts did you use?


 



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3/16/2016 10:14:37 PM EDT
[#2]
Alright I haver a thunder gun upper receiver a flag away carbine length gas tube a DEZ Tacticle fsp gas block a psa bcg a shore tactical 16inch 223 Wylde barrel 1/9 twist a a2 birdcage flash hider from my buddy's s&w ar a MAS defense millspec buffer tube with buffer and spring now the site does not specify on what kinda buffer it is it only says the weight  which is 3 oz that's the upper, a Anderson lower  with MAS defense lower parts kit  I've shot federal green tip and federal FMJBT I have shot a total of 80 rounds out of it and threw the 80 round I continued too have hiccups and I used three different magazines as well a GI mag a magpul gen 2 mag and a lancer mag
3/16/2016 10:29:54 PM EDT
[#3]
It could be your buffer spring. I've run into that before.

Make sure your BCG is well-lubed.

Put your upper on a different lower. If your upper works on a different lower, the problem is in your lower. If the upper doesn't work on on a different lower, try a different BCG, and so on.
3/16/2016 10:40:38 PM EDT
[#4]
Alright thank you I'll try that I'll post my feed back when I find out
3/16/2016 10:58:58 PM EDT
[#5]
Couple of comments that are frequent sources of problems:

Gas block alignment - most gas blocks should be offset forward from the barrel shoulder to compensate for the thickness of a handguard ring, if no handguard ring is used.

Loosen and then slide the gas block forward and take a look around the gas port, there is generally a ring of fouling that will indicate where the gas block is aligned.

And aluminum gas blocks are a really bad choice.

I recognized PSA and Federal out of your list of parts. I find that sticking with names that I recognize rather than no-name tacticool vendors for parts usually results in a much more satisfactory AR15 experience.
3/17/2016 11:40:01 AM EDT
[#6]
Quote History
Quoted: Gas block alignment - most gas blocks should be offset forward from the barrel shoulder to compensate for the thickness of a handguard ring, if no handguard ring is used.
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This is exactly where I was going to suggest starting. First build, clamp on block, I bet that thing us butted right up to the shoulder. Don't feel bad, most of us have done it at some point, which is why we advise looking at it. You can buy a shim to stick between the barrel's shoulder and the gas block for proper spacing. My personal preference is set screw mounted blocks on a pre-dimpled barrel.
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