I have a friend that I used to work for on the side that mfgs. tracer,incendary,and starburst bullets/ammo. Remington and Winchester didn't come out with 7.62x39mm brass/ammo till the mid 1990's. Starting about 1990 as sales of SKS rifles went through the roof there was a big jump in demand for 7.62x39mm tracer/incendary ammo. So we pulled bullets on dozens of cases of Chinese ammo to get the primed cases to load the bullets we made. I also started doing this in the late 1980's to load Hornady soft point bullets for deer hunting as there was no soft point 7.62x39mm ammo made at the time.
The Chinese ammo we pulled the bullets from was mostly steel core surplus but in a pinch when someone would order a couple 1000rds of tracer and were in a hurry. We would have to run out and buy a couple cases of ammo of whatever we could find which was most of the time Chinese commerical ammo. Some of the Chinese powder would ignite tracers and some would not so we did a lot of weighing powder charges when we pulled the bullets. Then recharge the cases seat a tracer bullet and test to see if the powder would ignite the tracer. We found that finding a powder charge that was even 1/10 of a grain off was rare and the same with the Chinese bullets.
Which is unlike the 10rds in the two boxes of Russian ammo I pulled and recorded.