Ar Gas Tube

[Religious Shooter]

Cleaning one of my uppers today. Noticed that the gas tube was blackened and crusty on the outside with carbon from the FSB to about five or so inches towards the chamber.

I remembered a gas tube incident at the 2005 RM3G. Don't want it to happen while during a major match. This particular gas tube probably only has 2-3K rounds through it. When are you supposed to change these things? MTBF?

[George]

When they break ;-)

Seriously, my CTR-02 has the same darkening from the gas block back about 4-5 inches. I regularly dribble Kroil on the tube and scrub it with a rag. This removes carbon buidup from gas seepage at the gas block joint but the darkening of the tube itself is normal in rapid fire useage like we put it to.

I replaced one in an older upper at about 17k rounds because I kinked it trying to figure out to remove the muzzle brake without the right tools.

I figure that re-barreling time is new gas tube time on an AR upper unless you do something ham handed like I did ;-/

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Regards,

[cking]

Gas tubes need to be replace when the little bludge on end gets worn down and doesn't provide a good gas seal.

Kind of hard to inspect the topside of it.

They last a long time if they are aligned correctly. That is something a lot of people miss when building AR's. most times a little tweaking is necessary.

If a good gun starts to have problems short cycling look at gas rings and tube and pickup thing on top of bolt for wear.

If you've worn down a gas tube, you also may have to replace pickup on bolt also.

[PacMan]

...

I remembered a gas tube incident at the 2005 RM3G.  Don't want it to happen while during a major match.  This particular gas tube probably only has 2-3K rounds through it.  When are you supposed to change these things?  MTBF?

<{POST_SNAPBACK}>

RS, that particular incident mentioned at RM3G was caused by a weakened gas tube in the JP adjustable gas block. If you don't have the first gen adjustable gas block, then your tube should be fine for many thousands of rounds. I pulled mine just because it is the first gen design with the gas screw on top.

[Carlos]

I took one out of a customer's gun once that was corroded/cracked about 80% through the hole for the front roll pin (its surprising it came out of the FSB in 1 piece).

I have a theory that it was a combination of gas cutting and cleaning chemicals that corroded that tube. If I use a strong chemical like sweets or any ammonia copper solvent, I follow it with a blast of break cleaner down the gas tube & a few mor patches of Kroil after that.

Anyone have a GO/NO-Go spec for the carrier end of the gas tube??