nifty-
You've presented a fine mystery with your description.
It's almost certainly a problem of powder reacting in some way with the brass, as Denton pointed out. The real puzzle is that the same reaction did not occur with your 250 Savage loads made from the same lot of VV-140.
Internet firearms forums point to VV-140 and VV-150 as being involved in several similar episodes of corrosion of reloads. It seems more frequent than it should be if the corrosion were associated randomly with various powders. The effect may be confined to various lots of the particular powders.
Here's a link to a thread in the falfiles.com forum, with clear photos:
[b][color:#000099]Has anyone else had Vihtavuori N140 corrode in loaded ammo?[/color][/b].
Google finds other web reports of corrosion from the same powders.
What seems odd to me is that, in both your case and the ones reported on that thread, the powder granules from the corroded cases do not appear different than usual.
Just out of curiosity, does the green stuff dissolve in water? Although it's been a long time since my General Chem course, I think Copper Nitrates are water soluble. (Copper sulfates are also water soluble, but there are not many sulfur-containing compounds in smokeless powder, I think.)
If the green stuff does not dissolve in water, it might be a copper carbonate. CO2 is probably one of the breakdown products of smokeless powder, and is responsible for the green patina on copper roofing, the Statue of Liberty, etc.
Curious.
--Bob
