The early Wolf ammo was lacquer coated and caused a build up in the chamber of some guns when fired rapidly and heating up the barrel. The newer polymer coating is not supposed to cause those problems. There probably is still some lacqer coated stuff out there, I would avoid it for an AR.
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I recently bought some TulAmmo as it was really cheap and will be good to practice with , I havent shot any yet but its all russian made like the Wolf however it doesnt have any lacqer on them. I bought 220 rds in boxs of 20 for $55 well I only spent $36 of my own $$ as I had some dicks sporting goods point cash and coupon to spend . They had $6.99 on the shelf but they matched Walmarts price of $4.97 @ box