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6/24/2025 1:22:31 PM EDT
ar15 micro 4 inch when using changing handle to load chamber the battery won’t shut all the way a tiny gap will can be seen, Same with using the release lever to chamber the round it won’t shut completely can still see a tiny gap still at battery, i used the same lower for a 7 inch 556 and no problems at all once I put the 4 inch upper on and the problem is there, can anyone think of what I’m doing wrong or not seeing right away, the lower works perfectly. Thank you.
6/24/2025 4:33:37 PM EDT
[#1]
Gas tube in too far, holding the BCG from closing?
6/24/2025 4:34:07 PM EDT
[#2]
drop a round into the chamber and then close the bolt. if it still does not close then something is off. First thing I would check would be to remove the gas block and tube. If it is too long the bolt can not close. After that then check the head space on the barrel.
6/27/2025 5:16:42 PM EDT
[#3]
Make sure your gas block and tube are installed correctly.
6/27/2025 10:24:05 PM EDT
[#4]


end of gas tube should come to here in receiver.

If farther back, then could be gas tube is correct length still, but instead of seated all the way into the gas block for the roll pin to go through the end of tube channel, the tube is not deep enough and pin is push through in front of the end of tube instead.

Short of that, check to make sure center of barrel feed ramps are centered on center line of front take down lug, and that barrel nut top channel/spine as correctly indexes so gas tube in not binging in upper receiver channel for it (tube should be free floating), and that the gas tube was indexed to not bind in carrier key as well.  If gas tube need to be tweaked to index on carrier key with not binding, then tweak gas tube over center of barrel.

As for checking gas tube to key, remove bolt from carrier, and with carrier and key alone, insert into uppper, push carrier until it touches the face of the barrel extension, then tilt muzzle upwards,and carrier should free fall back.
Posted By PlaymoreMinds:

'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...

<---skips away in frilly skirts to Candyland, leaving gutters and snorkels FAR behind.
6/28/2025 9:24:48 AM EDT
[#5]
same bcg or different bcg?
The deuce you say.

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