It sure can be. If you use the right bullets, the 7.62X39 can beat the .30/30 factory loads. I have two of them, an SKS and a CZ 527 carbine. Both of these rifles will fire a 150-grain Sierra spitzer .308" bulletat 2300 FPS using a max load of H335 powder, and they will both break 2000 FPS using the Speer .311" roundnose 180-grain bullet again with a load of H335 powder. In addition, both of these loads are accurate, of course they shoot better from the CZ than from the SKS!
If you are forced to use factory ammo, try the recently introduced Wolf brand in the 150-grain softpoint load. I think Sportsman's Guide has this ammo, and I would use a 150 grain bullet in preference over the 123-grain stuff.
JUST DON"T use any FMJ ammo!
The CZ carbine is very accurate, even with .308" bullets, as you can see. The upper three-shot group was with Winchester FMJ 123-grain ammo, not suitable for hunting. But the Sierra 150's would do in any deer!