I've killed a good number of deer (11 I think) with the 7.62x39 out of one of those "inacurate" Mini-30's. I bought a pawnshop Mini-30, gave it a trigger job, trigger shoe, x-power hammer spring, x-power recoil spring, AS adjustable gas block, Nikon 2-7x32 scope, and worked up a handload using H335. I'm pushing 2600fps+ with the 125gr Sierra SP. Plus, with the heavy recoil spring and gas block it has very little recoil. About like a .22mag. My 98lb wife and 74yo father have no trouble shooting it. The crosshairs don't even leave the target when fired from sandbags at the bench.
Oh, and after the mods it will do around 1.125" at 100 yards and around 3" at 200. I'm 5.75" low at 200 yards when sighted in at 100 yards, and only 10.5" low at 250 yards. There's still over 1000ftlbs of energy at 250.
For comparison, my 336 .30-30 is sighted in at 100 yards with the 140gr FNSP at 2650fps. It is 6.75" low at 200 yards and 13.5" low at 250 and drops below 1000ftlbs of energy at 210 yards.
So while there are plenty of guys out there that will tell you the 7.62x39 is no .30-30, in a way they're right. In some cases the 7.62x39 is better than the .30-30 in retained energy and trajectory.