I have an M/2 that I've owned for over 40 years. I shoot only my own cast bullets and still use the same powder I started out with in the '60s, Alliant (then Hercules) 2400. I get full function in either mode and it appears nearly eternal case life with the stuff!
I originally stuffed about 13.5 under a straight wheelweight Lymans 120 pointed gas check but have backed down to about 12......only because the cases I have are a mix of military and commercial stuff that varies in capacity. Accuracy level seems to be just about what one would expect with fmj surplus stuff. It works, I like it so I'll just keep on with it.