I've got several boresnakes that I keep in a ziplock bag.  I use them for quick cleanings and put Hoppes No 9 on them when I run them through the barrels and then put them back in the ziplock bag.

Well, like a lot of people, I haven't done nearly as much shooting the past 12 months and so the boresnake bag has sat for quite a while.  Today, after getting back from the range, I went to do a quick barrel clean with them and noticed a lot of green corrosion (?) on the brass end of the boresnakes.  It cleaned off fairly easily, but it had me a bit concerned.  Is that some sort of chemical reaction of the gunpowder and Hoppes No 9 along with the brass?  Something else?  Is that normal for leaving them like that for a few months?

Also why you shouldn't use Hoppe's No 9 on anything with a nickel finish, including GLOCK small parts.

I find this interesting.  

Generally, I only use Hoppes No 9 on bore cleaning and then use standard Break Free CLP on everything else.

#9 is formulated to gently help dissolve and remove copper/brass jacket fouling. So, it should not be a surprise that it can be detrimental to bore brushes as well (it is). Brushes don’t last forever.

ETA- Personally, I use a mil-spec CLP with my bore snakes. Also, a bore snake is good for quick field maintenance but not really a substitute for a proper brush and patches cleaning, IMHO.