Copper jacket?

[richtam123]

I found this .22 casing in a heavily wooded area. It's of normal size of a .22 but the sheer amount of patina is surprising. I thought heavy green patina only formed like that on copper, not brass. So far it's been impossible to remove it on the bottom to read the headstamp. Any idea how to remove the patina without destroying the metal?

 

[golden ray]

In the making of brass, copper is the number one material they use.
Yellow, red, bronze, hi-grade, etc. all these types of brass contain a
different mixture of copper content.

 

[richtam123]

In the making of brass, copper is the number one material they use.
Yellow, red, bronze, hi-grade, etc. all these types of brass contain a
different mixture of copper content.

Aha, that makes a lot of sense...thanks