I've been intrigued by this rifle but haven't "bit" yet. I ended up finding a CZ 527 in 7.62x39 for a good price when I was making that particular decision and went that route, BUT...
I agree with the many who assert how the cartridge is a great CB-shooter. I also agree with
@Mitty38 that brass is more of a pain to locate/acquire though. I have a fair bit, bought new from Starline, but I gave the Russian up in deference to the 30/30. NOT that the 30/30 is "better," but better for MY needs/uses.
STILL, the 7.62x39 is one of those "naturals" when it comes to cast. Very pleased. My results mirror that of
@Intel6 's regarding "best bullets," but my lightweight was the "Soup Can" again, because mine casts .313" and I removed the GC shank (now 118 grains), and the very same RDO 150 (made FOR the cartridge) shines on the heavier end.
BUT (another one), if I were doing this again, say adding another 30 cal., I'd opt for the 300 BLK again. The brass situation is so much more convenient, for one thing, and I never bought a single round of new 300 BLK brass, mainly because it wasn't even available yet when I got mine. The LEE "Soup Can" was its favorite light bullet and the RDO 311-165RF it's favorite heavier bullet - just like my 30/30.
the 300 BLK is a dandy for cast and I tried to interest some other cast bullet folks that it was worth a look, but the consensus at the time was that it was another has-been-before-ever-being rounds, a fad which carried baggage - a stigma relating to the affliction for falling for something renamed and sold as "new." Nobody listened. Now, look at it. It hasn't fallen flat and I believe it has as much to do with how useful it is as how "cool" it is, even if it's not exactly the latest/greatest cool, new thing now.
The smaller case capacity makes it a natural for the small doses of faster-burning pistol powders AND for the slowest-burning pistol powders, which suit its own top-end capability. In my mind, I don't see rifle powders having much chance to offer a lot more versatility. Very convenient, efficient, economical, compact, easy-to-acquire (as in
make) brass, available in some really neat, really compact guns - or an AR if that tickles one's fancy. Mine was a AAC/H&R Handi-rifle. What a cool little gun.