A source for zinc-plated 7.62x39mm "Silver Bear" a
The zinc-plated-steel-case Russian Barnaul ammunition is marketed in the USA under the "Silver Bear" trade name. Barnaul also makes the "Golden Bear" (brass-plated steel case) or "Brown Bear" (lacquer-coated brown steel case) rifle ammunition. A few calibers are made by Ulyanovsk and Novosibirsk LVE. It is pretty good stuff. You can see the "Bear" cartridges offered by clicking here:
I've fired it, and it gets the job done. It's cleaner-burning than the Wolf polymer-coated steel case JHP, with slightly higher velocities and (slightly) better accuracy, all for a (slightly) lower price.