"black" lake city 5.56 ammunition.

[PriestFoxley]

Every time I go out to a military range near fort Bliss, I notice jet black looking ammunition. brass cases that look solid, smooth black, same with the fired rounds.

I have no idea how old they are, but during the last range, I brought a set of calipers with me and measured an unfired, "black" round. tolerances for a 5.56 seemed normal, and a bit of scrubbing with a brass brush proved the tarnish didn't come off easy.

Now, I just got into reloading, and I can't help but think that black cases like that look cool as hell. I am pretty sure it is an effect of the environment, but no clue what exactly. the sun, maybe?

I dumped a handful of .308 unprimed brass on my roof a month ago. They look a bit dull, but not black.

Just how long do the cases have to be exposed to turn black? what the heck actually does it, and can I duplicate it in a faster way?


I know there is no good reason to do this, but it is science, and sorta cool.