I've shot several thousands of rounds of Wolf 7.62x39 in my sporter AK and SKS rifles without any problems. It's Russian lacquered steel-cased ammunition, as you know, and the old Soviet military specification provided for steel-cased small arms ammunition. As a matter of fact, the Russians (and the old Soviet Union and it's client states) provided for steel-cased ammo production at all times, not just war contingiencies. The bullet jackets may be guilding metal-clad steel as well, and function just fine. Bore wear is no greater than using "copper" jacketed bullets.
US military ammunition specs also provide for steel-case production, but that is usually only in effect during wartime shortages. America is a wealthy nation, and can afford to use the more expensive (and recyclable) brass in it's ammunition.
You'll notice that the extractors on the AK and SKS designs are particularly massive and rugged. They are made that way for durability.
The Russians apparently still use dirty-burning powder, and you may experience more firing residue than with commercial ammo.
Some users report extraction/ejection problems with the .223 caliber steel-case ammunition in AR-15 type rifles, but to my knowledge, the 7.62x39 has no such user complaints. I would test -fire some batches before stocking up on this stuff.
