Gas tube wiggle question

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Benito

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I was cleaning my 308 AR today and noticed that the gas tube has a bit of play inside the upper receiver. Not much, but enough to make a sound when moved side to side, and up and down.
My main concern is that it goes out of alignment with the gas key, and the force of the BCG (pretty damn heavy on the 308's) cracking something when it slams forward.
Any ideas on how to remedy this/thoughts?
 
The tube's position is set by the gas block which should be indexed off the gas vent hole in the barrel. The (minimal) play is perfectly normal, but you should have to work a bit to see it. If it is easy to move, something might be loose or off. If all is aligned properly, your carrier should slide in with no binding with the tube. If there is you may well have issues with (typically) vertical stringing of groups. If it binds enough you may have to check and/or make corrective action to some of the alignments.
If your gas block is put in with set screws, check their torque and ensure they have lock tight. Check to ensure the role pin hasn't started to walk out of the tube or gas block.
 
I think the op is saying that there is play in the hole where the gas tube goes into the upper receiver, not necessarily that it's loose in the gas block.

The end of the gas tube that's in the receiver has a slight chamfer on it and the gas key also has a slight chamfer so as to allow a 'funneling' action. As long as that gas tube doesn't have too much play it should enter the gas key just fine. Try pushing the gas tube to one side and close the bolt slowly with the charging handle. As long as it doesn't catch, you shouldn't have any issues.
 
My two cents:

Look for wear on the gas key and gas tube in one spot more than another: this would show the "wiggle room" is causing an alignment problem. In other words, if the 3 o'clock position on the key and the tube both have more wear...

Other than that, even with a bit of "play" the system could be fine.
 
*MALICE* said:
I think the op is saying that there is play in the hole where the gas tube goes into the upper receiver, not necessarily that it's loose in the gas block.

The end of the gas tube that's in the receiver has a slight chamfer on it and the gas key also has a slight chamfer so as to allow a 'funneling' action. As long as that gas tube doesn't have too much play it should enter the gas key just fine. Try pushing the gas tube to one side and close the bolt slowly with the charging handle. As long as it doesn't catch, you shouldn't have any issues.
Click to expand...

:agree:
 
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