Here's a quote from Wikipedia on the 7.62x39mm cartridge for hunting. I like the part about the poor person's deer rifle LOL!!
"Since approximately 1990 the 7.62 x 39 mm cartridge has seen some use in hunting arms in the US for hunting game up to the size of whitetail deer, as it is approximately as powerful as the old .30-30 Winchester round, and has a similar ballistic profile. Large numbers of inexpensive imported semiauto rifles, like the SKS and semi-auto AK-47 clones and variants, are available in this caliber, and the SKS is so inexpensive as to have begun displacing the .30-30 lever-action rifles as the new "poor person's deer rifle." Inexpensive imported 7.62 x 39 mm ammunition is also widely available, though much of it is of the non-expanding type that may be illegal to use for hunting in some states. However, there are a number of American civilian manufacturers which produce soft-tip rounds, suitable and legal for hunting."