I buy 7.62x51 FMJ by the case for my Garand and SMLE 2A-1 whenever it's cheap. The only HPs I've ever run through them have been 168 gr. Match ammo when I used to compete with the Garand regularly. I save the SPs for my hunting rifles.
Simple matter of economy for me, as surplus FMJ costs a small fraction of what commercial HP or SP does. I reload .308 for my hunting, but stopped doing so for the Garand as I can buy all the plinking/hoarding ammo I can use as surplus cheaper than I can crank it out myself.
In 7.62x39, I go with whatever's got the best price at the time. I've run some commercial SPs through my Mini-30, but have steered clear of them in my SKSes after a memorable FA event several years ago. FWIW, I haven't run across a brand of HP that would expand reliably, Russian, Chinese, or whatever.