What's corrosive in 7.62x39 ammo?

[ElvenSoul]

I don't know why but cleaning cosmo off in the oven and washing guns in the bath tub just freaks women out. I mean really freaks them out!

[MrPlink]

I treat anything with a berdan primer as corrosive.

In the old days I'd see ads listing ammo as 'mildly corrosive'. Always made me laugh.

-Dave

might have been a fair rule of thumb maybe just 5 years ago but there is honestly no point for that heuristic now.

I never understood why people laughed at mildly corrosive (and would claim it is analogous to mildly pregnant). I may have barely passed high school chemistry, but I have no misconceptions in my understanding that some things are more corrosive than others.