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Discussion Starter #1
I built my first ar. Used Aero upper and lower, Kreiger barrel, supplied gas block and tube, PSA bolt, Hyperfire trigger, Mlok forend. Problem is that it wont run from mag, fire and cycle bolt to eject fired round. Checked gas rings and they are not lined up. Using 25g Varget and a 55g Btip.
 

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It's leaking gas. Check around the gas block & look for carbon blow by around the barrel, around the gas tube & gas block. Gas can leak around the gas key on the carrier, as well as the end of the gas tube & gas key.

You can use Green Lok Tite to seal around the gas port and gas block. Apply a thin bead of Lok Tite around the gas port, re-install the gas block. Allow the Lok Tite about 23hrs 59 minutes to set before shooting.

Other things to look for:

Look to see if there is a distinctive "knob" on the end of the gas tube.



If any of those points do not correct your issue, pull back on the charge handle slowly & feel for any binding.

I did encounter an issue one time where the buffer tube was screwed in too deep and the buffer was not traveling far enough when the bolt cycles. The buffer tube should only be screwed in far enough to cover the shoulder of the buffer dtent.

This is what is should look like:



Buffer tubes with a notch in them, when screwed in too far can cause the buffer to bottom out too quickly in the cycle & bounce putting too much forward momentum into the carrier.

 

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Is your gas block backwards?

Should be able to blow in the tube and feel air coming though the block.
 

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Take upper off lower and plug chamber area. With bolt carrier removed, blow air into the muzzle. You should get plenty of air coming out the gas tube. Be sure the gas port on the barrel and gas block are not plugged. I have seen that, or gas tube upside down with hole facing away from barrel. From here it sounds like you're getting little or no gas.
Or if in Dane County area we can meet and get it sorted out.

Steven
 

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I agree, you're leaking gas somewhere. Forget about the bolt rings - a rifle will function with only two rings, assuming that it functioned with three. Make certain that your gas tube is correctly installed and that the spring pin isn't broken. While extremely uncommon, I have seen it happen. The most common culprit is an incorrectly installed bolt carrier key. Next is an ill-fitting (or incorrectly installed) gas block. I assembled an AR pistol on the cheap a while back and the Chinese gas block that I used leaked gas like nobody's business until I applied Loc-tite to seal it.
 

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Take upper off lower and plug chamber area. With bolt carrier removed, blow air into the muzzle. You should get plenty of air coming out the gas tube. Be sure the gas port on the barrel and gas block are not plugged. I have seen that, or gas tube upside down with hole facing away from barrel. From here it sounds like you're getting little or no gas.
Or if in Dane County area we can meet and get it sorted out.

Steven
Yep! This (above) works like a charm!

I used compressed air from my air compressor, plugged the chamber, and while running air into the muzzle, I maneuvered the block for max air escaping from the tube. Satisfied, I then clamped down the block (with a little BLUE LockTite on the barrel around the gas port to better the seal).

I used a JP Industries variable gas block. That way I can shut off the gas completely to comply with certain (semi-automatic) range rules. AND, to frustrate certain scrupulous brass scroungers -found at "many" matches - from pocketing my ($.60 to almost $1/ apiece) LAPUA match-prepped brass before it even has a chance to cool off, leave alone before the relay has ended when I can retrieve them myself!:rolleyes:)
 

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Discussion Starter #7
I plugged chamber and blew air and got what I thought was good air out of gas tube. I took to the gunshop to see what they say. They build ARs there.
 

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I plugged chamber and blew air and got what I thought was good air out of gas tube. I took to the gunshop to see what they say. They build ARs there.
Did you notice air coming from ANYWHERE it's not supposed to? That idea can also po in not out any leaks in the system as well. Also try pressing a pencil eraser over the gas tube (the end in upper). That will really show any leaks in the system. Also loosen the gas block and turn it each way slightly, if you notice air volume increases the block is not centered over the port.

Steven
 

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ttt:D
 

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Discussion Starter #10
As a follow up, just shot it today and am very happy now. It runs like it should and shoots like a Kreiger should. It turned out the gas block hole and the barrel gas hole did not line up properly. They shaved some off the back of the block and it is working. Don't know why I could blow in there and get air but must not have been enough.
 

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As a follow up, just shot it today and am very happy now. It runs like it should and shoots like a Kreiger should. It turned out the gas block hole and the barrel gas hole did not line up properly. They shaved some off the back of the block and it is working. Don't know why I could blow in there and get air but must not have been enough.
Glad you were able to troubleshoot it. Who's gas block did you use? That measurement would have to be very precise; no room for any hungover machinist when drilling those holes!

BTW, my new UPPER is sporting a Krieger bbl as well. After seeing a one-hole 5-shot group(s) my bro was getting with his new Krieger upper, I too went with one (w/ a Wylde chamber too*, BTW).

I threw together some break-in rounds to also rough in the scope at the same time. GEEZE will this thing shoot! And, I haven't even fooled with optimizing the load yet! (~3/8" C-C for 5 @ 100 yards :))

Eye candy:
 

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