M16A1 metsl flaking issue?

[HOOKED ON HISTORY]

I am gathering parts for a retro AR and have found a couple of M16A1 uppers that seem to have some sort of deteriation of the metal. Does anyone have an opinion as to the cause of this? Would this render an upper unsuitable for use? Could it be repaired and refinished?
Metal in the affected areas can be flaked off with a fingernail.

Information

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[browningautorifle]

Oxidization? As in rust? Where was it stored? It looks like it's deteriorating. I'd bead blast it and have someone redo the finish. I had Olympic in Olympia Wa do an upper about 25 years ago. Must be someone around that'll do it?

[HOOKED ON HISTORY]

It is from a parts kit. It is amazingly soft in the affected areas. I am going to try and get a better one before resorting to restoration. Want the build to look used but not used as a boat paddle.

[browningautorifle]

You should be able to find one around here...

[imarangemaster]

On the aluminum, the surface is hardened. If the surface is worn away, the interior is soft. Maybe exposure to salt water?

[HOOKED ON HISTORY]

On the aluminum, the surface is hardened. If the surface is worn away, the interior is soft. Maybe exposure to salt water?

That seems to be the case, The finish is gone and it does seem to be worn beyond the surface layer. I wonder if there is a way to repair the soft evposed areas and refinnish? Perhaps cericoat?

[imarangemaster]

You could bead blast it to get loose, deteriorating material off, then use JB weld, file. Then you couldfile it, fine sand it, then Cerocote. JB weld is very tough and would work great.

[Bruce McAskill]

The metal is just going to continue to disintegrate. It's like rust but the aluminum version. Once the salt got below the surface it was all over for it. Even if you were to blast it the metal will continue to come apart and will finally fail. Like any iron or steel that's been in salt water for a long time it has to be treated with a long period of being in fresh water and that takes years to leach out the salt. It's close to failure now so you would be better off looking for a new one. This one is gone.

[jmoore]

The metal is just going to continue to disintegrate. It's like rust but the aluminum version. Once the salt got below the surface it was all over for it. Even if you were to blast it the metal will continue to come apart and will finally fail. Like any iron or steel that's been in salt water for a long time it has to be treated with a long period of being in fresh water and that takes years to leach out the salt. It's close to failure now so you would be better off looking for a new one. This one is gone.

Previous eperience with this sort of corrosion in aircraft structures compels me to agree. It's toast. The intergranular corrosion will usually have penetrated quite deeply into the metal before the external apperance gets this bad. No hope for it, and could be more unsound than most folk would suspect.

BTW, usual culprit are chemicals on the alkaline side of the p.h. chart. The stronger alloys are more prone to corrosion. In this case, likely 7075. Probably T6 or equivalent heat treat, not that it matters much. 2024 will fizz nicely, too.

[HOOKED ON HISTORY]

This upper if from a parts kit of unknown origin. The vendor has sent the original and three replacements two had this corrosion issue the other two had mechanical defects. Perhaps the fith time will be the charm.