So I came across something in my barrel that has me stumped. Few years back I bought a complete BCM upper to throw into storage. I do pull it out every so often (2-3 times a year) to punch oil down the bore. Here is where the mystery begins; I recently acquired a bore scope and decided to have a look down all my barrels. This one in particular was absolutely ridden with what appeared to be rust, a yellowish orange-ish layer. I started brushing it out with solvent, but all my patches came out black and blue. Furthermore, with 99% of things cleaned out there does not appear to pitting. So my question to you fellows is, was my bore rusted? This picture was taken after a few brushing cycles and does not reflect what it looks like now
It appears to be copper fouling.
Thanks!
Not an uncommon problem. Try some Wipe Out with or without the accelerator. You'll be surprised how much blue comes out with it.
Nice, appreciate the advice. I could have sworn with the color it was rusted, but with everyone’s advice (I did hear back from BCM and they agreed with everyone here) and the lack of pitting it seems to point towards copper fouling.
This one has been in storage the entire time I’ve owned it. I plan on taking it out my next outing
