Well, the .30-30 normally does have a power edge over the 7.62x39, even if it's not huge (about 10% if I recall), and also with the .30-30 being a game cartridge and the 7.62x39 being an antipersonnel cartridge, there are offered more game bullets for the .30-30: 170gr soft points, 150gr Barnes X-bullets, 170gr Hawk Flat Nose, 170gr Nosler Partition, etc... these kinds of heavy, limited expansion rounds will offer deeper penetration than the 125gr hollowpoints that are standard 7.62x39mm fare.