Took my Bushy m4 out last weekend, put a 60 or so rounds of Igman ss109 and Olympic ss109 through it to test some Orlite mags.  Both ammo and mags worked great, no hicups.  

Well I took the rifle out of the case today to put it back in the safe, and I noticed this green crud on the inside of the mini y comp.  It kind of looks like the color of copper after its been weathered a bunch.  

The chamber is fine, nothing out of the ordinary.  Any ideas what this stuff is or how it happened to showup?  

Thanks,

MG

Sounds like corroded copper to me.

But on another thread I posted "the stupidest post ever on the entire internet".....so, take what I say with a grain of salt.

Could have been boogers. [:D]

I thought the Olympic SS109 had green-tipped bullets?  Maybe that's flaking off and piling up in your brake.

jafager

From my own experiences -

The green is deposits from the last time you cleaned your barrel.  You used Hoppe's or some other barrel cleaner that slighlty dissolves copper.  The cleaner deposited the dissolved copper in the mini-y ports.  You did not see it before because the oil (from Hoppe's or CLP) covered it up.  The deposits do not appear as green color when "wet" with oil.  So, you now go shooting, which burns off the oil from the mini-y.  Now, the copper deposts are no longer "wet" with oil.  Now you are able to see the deposits in the mini-y.

If the green bothers you, use some Sweets on a Qtip to wipe it out.  Be sure to rinse the Sweets off very well.