The 1260 on the edge of the lid?Just a guess 1260 rounds? that would be the 4 digit #
Typical AK food that is corrosive. Did an AK come with it?
Funny thing is. Back in the 90s/early 2000s when all the new surplus was coming in I'd see shooters at the range shooting corrosive ammo. While talking I'd ask if they knew how to clean it. If I mentioned hot water on a couple patches first I'd get squint eyes telling me water will rust guns so no way they are putting it in their barrels. If I said squirt some Windex(pretty blue water and sudsy ammonia) I'd get OH YAH, thanks. So "Windex" of any style is my default telling shooters on cleaning corrosive ammo.I used to use windex, but really all you need is water. What makes it corrosive are the salts left behind, and a good douching with water will get it out. finish it off with compressed air and oil, and it's fine.