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1/25/2018 7:38:29 AM
Posted: 12/18/2005 9:41:02 AM EST
[Last Edit: 12/18/2005 9:50:32 AM EST by Gold_Cup]
I have a newly assembled upper that I took out to the range for the first time. I was only able to shoot 20 rounds or so before the bolt refused to go forward all the way.

I took the bolt from my new build and compared it to a factory RRA upper and it slides in n' out w/o binding. I've compared charging handles with calipers and I don't see anything that is out of line. The inside diameter of the gas keys is the same for both bolts as well.

I assume I need a new gas tube since the "good" bolt and charging handle are binding on the new build as well. What is the best method to ensure that I install this gas tube correctly? After I tightened the barrel nut I inserted the gas tube in the receiver and into the FSB. It wouldn't go in all the way so I took a dowel rod and a light brass hammer and lightly tapped the gas tube into the FSB so I could get the roll pinned aligned. Is this the correct way to install, or should I remove the FSB first, insert gas tube into FSB, tighten the barrel nut, and then slide the FSB with gas tube on into the receiver?

Are bad gas tubes common, or was I just a donkey and bent mine when I installed it?

Any other places I can measure to be sure my gas key, bolt, or charing handles isn't the problem?


The measurement from the top of the carrier to the gas key is .261 for the new bolt and .260 for the factory bolt. Inside diameters of the gas keys are .178 for both of the keys.
Link Posted: 12/18/2005 1:10:40 PM EST
My gas tube measures .182 at the end that goes into the FSB.

The part that goes into the carrier measures .182-.185. I think the spec is .180 for the gas tube.

.180 drill bit goes into the carrier easily, .182 drill bit goes in about 3/4 of the way and then gets stuck.

Time to buy a new gas tube.

Link Posted: 12/19/2005 4:01:08 AM EST
Link Posted: 12/19/2005 4:21:52 PM EST

Have a new gas tube on the way.
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