.30 cal. Aluminum Gas Checks.

[Glen]

No, the aluminum is not coated to prevent oxidizing, and yes it does have an oxide coat. However, it is pretty thin (in the context of this discussion), and the oxidation is a self-limiting process because the oxide coat is durable and passivates the metal surface. Yes, aluminum oxide can be an abrasive (depending on how it is presented to a surface), but I doubt that's going to be a problem here.

 

[Ian]

Yodog, thin of it like this: If oxidized aluminum surfaces were particularly abrasive to steel, the AR-15 wouldn't exist. Abrasive grit deliberately created from oxides of aluminum and used to make sandpaper or blasting grit, and applied to steel via rubbing or blasting, now that is a different story. I think people get confused at the difference, like how can you make lubricating oils and greases out of sand.

 

[fiver]

or clay, or silicone [silica]