7.62 x 39 What Did I Buy ??

[Iron Glove]

At the last HACS Show I picked up a grab bag of 7.62 x 39 for the SKS from a delightful elder citizen who assured me it was non-corrosive.
Head stamped 9121 over 74, is copper or brass coloured with a red ring at the base of the bullet and a black ring at the base of the case.
Can't post a pic 'cause I'm at the cabin.
Wonderin' what I actually bought.
Thanks.

 

[CanAm]

Chinese surplus corrosive

 

[Iron Glove]

Thanks - at least it was cheap, I sorta thought cheap = corrosive but this stuff is just so darn pretty looking.