OK, I slipped down there today in spite of the cracked heads. The load I used was 23 grains of the IMR 4198 under the Speer .311" 180 grain RN's. This gave me 2,050 FPS on average and is about as hot as I care to go. I could probably squeeze a bit more powder in there since I'm not actually at the limit of the magazine's OAL capacity. But I like it right where it is. Accuracy with these .311" bullets was MUCH better than with the .312 high-ogive woodleighs. I got a single half inch hole just below point of aim at 25 yards and a nice 2" group at 75 with iron sights in very bad glare. I'm confident that could be cut down smaller with better light conditions or a scope.
The ft. lbs. on this load are about 1680 on average. Not exactly magnum-levels, but those 180's have a sectional density of .266. This would be a perfectly acceptable round for large black bear, hogs, large deer or moose for inside 100 yards. Not sure about elk, as I have no experience with them. No, it's not going to get you into .30'06 power levels, but the carbine in question is a 5 1/2 pounder that totes like a handgun. Recoil even with the maximum load is minimal.
Unlike Woodleigh, Speer doesn't list the specific range of ideal velocities at impact. However, Speer says these Hot-Cor styles "promote reliable expansion even at lower velocities." So I should be good as long as I don't push the range.
So that's the end of that experiment for now. I think I've at least proven that the 7.62x39 can indeed be loaded to match the .30-30 with heavy bullets. But I'd only suggest trying this sort of thing in a mini-Mauser or Ruger M-77. I would NOT advise it in the Mini-30, SKS or AK-47. I have no idea what these loads would do to the gas systems in those rifles.
The wee loads should be fine, as well, but I wouldn't go below 7 of Unique due to spike possibilities. And I don't want to risk a ringed barrel by packing dacron filler in a bottleneck case!
One thought--there was little excess flash with this load in spite of the very short barrel and large powder charge. The IMR 4198 seems to use its steam up in the short barrel. This might be of note to .30-30 handloaders who like to use the little spikehorn style carbines. One problem with those is the velocity loss and excess f&b you get with standard .30-30 ammunition. If you used 4198 instead of 3031 (with appropriate reduction in charge amount) you might be able to work up a very good spikehorn load.