I use it in all my firearms. It has given good results esp with the 7.62x39, the .308, and the .303Br. I use it in my .30-06, but it is starting to stretch a little thin for the .300 Win Mag. You could probably use it but it wouldn't be even close to the best powder for best performance it being at the bottom of the scale as it is.
That being said, I would probably use it myself if I had to load for that round since it is a less expensive powder.