Worn out Gas Tubes

[Red*Lion]

There are several ways to check the gas tube alignment.

A slightly misaligned gas tube can cause premature ware.

Not that I do not believe you, but how can a misaligned tube cause premature wear? I would think that misaligned would imply that it is impeding some of the gas flow?

[georgeib]

Not that I do not believe you, but how can a misaligned tube cause premature wear? I would think that misaligned would imply that it is impeding some of the gas flow?

He's referring to the alignment between the tube and gas key, not the tube and port on the barrel.

[markm]

Yeah. That'll rub one side smooth probably. These bad tube have no "step up" on the full circumference of the tube. Gas is just bleeding out of the key.

[HKGuns]

Dang dude, you don't need no guage to tell those are bad! I suspect your suspicions are correct on those tubes, that looks pretty bad to my eyes.

[georgeib]

I've had one gas tube wear out in the same way as Mark's. It was on an upper I had built back in '09 that wore out the bulb on the tube in under 5k rounds. Replaced it with something better, don't remember what but maybe a DD tube, and I think I've got at least 5k additional on that upper with the new tube. Haven't looked at it recently, but I think I'll pull it out of the safe and give it a cleaning and once over.

[prepare]

Not that I do not believe you, but how can a misaligned tube cause premature wear? I would think that misaligned would imply that it is impeding some of the gas flow?

georgeib correctly explained what what I was referring to.

[markm]

I've had one gas tube wear out in the same way as Mark's. It was on an upper I had built back in '09 that wore out the bulb on the tube in under 5k rounds. Replaced it with something better, don't remember what but maybe a DD tube, and I think I've got at least 5k additional on that upper with the new tube. Haven't looked at it recently, but I think I'll pull it out of the safe and give it a cleaning and once over.

I really don't pay too much attention to this, but if I clean a gun I'll take a peek. I pulled this tube yesterday and it had caked on fouling right about the area of the barrel nut. If this were a middy, I'd probably have figured it out sooner because I thought the middy tubes were the problem.

I can't wait to shoot this gun with a new tube. I remember running a suppressor on this thing years ago and thinking how well it was gassed. Now I know why it's weak with no can and good with a suppressor.

[bfoosh006]

Thank you for reminding me ( us ) about gas tube wear.

I would have forgotten to consider this as a function issue.

Sometimes I tend to forget these simple fixes.

Sorry if I missed it, and not that it matters, did you happen to have a approximate round count ?

[markm]

Sorry if I missed it, and not that it matters, did you happen to have a approximate round count ?

Best guess is a couple thousand. I've had the upper for many years, but it was not shot much and kept as a hedge on supply issues/bans, etc. You can tell by the pic that the upper hasn't seen a lot of rounds through it.

[ViniVidivici]

This is why I keep round counts on everything, in a maintenance log, so I know if something is wearing out earlier than it should, and when it's time to proactively change things.