Worn out Gas Tubes

[TMS951]

I caused an under gassed KAC upper that ended up being a gas tube in the same condition described. The ‘bulb’ was worn off.

I was very surprised to see this. This upper had one variable. It had been through a couple days worth of carbine class in a very sandy range. It was a deep mid to fine beach sand brought in to cover the range.

We did a lot of drills that got a lot of sand in the action. I remember cleaning it out of up where the gas tube was and the BCG being covered. The sand had stuck to the lube and made an abrasive compound.

[Disciple]

We did a lot of drills that got a lot of sand in the action. I remember cleaning it out of up where the gas tube was and the BCG being covered. The sand had stuck to the lube and made an abrasive compound.

Another good reason to use a nitrided gas tube it seems.

[markm]

Each time I've had this happen I've run a q-tip into the key to check for obvious rough surfaces. My old thought was that there was some bad/soft gas keys a few years back, but maybe Ned's notion of slightly rough/non-honed keys is the issue.

[georgeib]

Another good reason to use a nitrided gas tube it seems.

I'd rather replace a gas tube than a gas key.

[markm]

I'd rather replace a gas tube than a gas key.

Yeah. I trust almost nothing nitride/melonite. American Mediocrity has polluted that process too. We had first hand experience with a shit faxon barrel.

[Disciple]

I'd rather replace a gas tube than a gas key.

The key is already chrome lined. Are you supposing a smooth QPQ finish would damage that?

[georgeib]

The key is already chrome lined. Are you supposing a smooth QPQ finish would damage that?

If the goal, as you implied, to using a melonited gas tube is to decrease wear of the tube, then the wear is by necessity being transferred to the gas key. Though hard chrome is still significantly harder (~69 RC) than a melonited stainless gas tube (43-52 RC), the melonited tube will still wear the chrome. As will a standard gas tube, though at a significantly slower rate.

At the end of the day, I would rather wear out gas tubes than gas keys. I have one or two melonited gas tubes in a parts pin somewhere around here. I removed them, in part, because I realized that if they were of real advantage, they would have likely been specced long ago.

[markm]

I removed them, in part, because I realized that of they were of real advantage, they would have likely been specced long ago.

This! Much like the crap the SpringCo makes. If it was needed, it would have been a requirement.

[the AR-15 Junkie]

This! Much like the crap the SpringCo makes. If it was needed, it would have been a requirement.

Agree 100%

[markm]

Agree 100%

They've made a fortune selling nonsense/snake oil. Maybe Pfizer will buy them as a subsidiary.