I can't see the pic but from the description sounds like a pump AK?

Century had them advertised for about $200 for a while. I wondered where they went!

Ruger Mini-30 barrels were at one time .308 and maybe still are, but chamber dimensions allowed the use of .311 bullets. I've never read of any warning against its use, too, and most in terms of #'s of rounds of ammo used in 7.62x39 is .310-.311.

I shot lots of lead core steel-cased .310 factory and surplus ammo from my CZ527; no problems at all and my daughter shot one of the biggest bucks we've ever taken on the ranch here with that gun and Wolf HP ammo some years ago. I got rid of the gun due to feeding problems but as for shooting, it was tops; Wolf HP giving 2 3/4 inch 5-shot groups at 200 yards. I miss the thing, but don't miss the misfeeding...

Maybe steel-core ammo would present some problem, but I also would find it odd that the CZ would have been chambered to SAAMI spec. Wouldn't CIP or their own milspec seem more likely? Anyway, we never had any trouble with a wide variety of 7.62x39 in our CZ.