The ballistics on that round get pretty dismal out past 200-250. The cheap ammo I have bought of late has been some of the worst I ever used(Wolf). For long shots I would advise against the 7.62X39.

If you are working with a tight budget, or have imposed one to preserve matrimonial harmony, you can pick up a Stevens bolt-action pretty cheap, and it comes in some more appropriate chamberings for shots out to 350. Rounds like the .308, .30-06, .270, 7mm-08, or 7 mag would be good for deer or coyote out to that distance. .223 is very popular for coyote, but some folks don't like shooting deer with it. I hunt deer with the .223, but most of my shots are well within 100 yards. I don't think I would shoot a .223 at a deer much past 200.