I've used with a bit of StaBALL 6.5 in my 300WM. I'm shooting 151 absolute hammers at 3,460 fps. Ran as high as as 3503, but groups opened up. Settled on 79.5 grains running .4-.5 mo.How do you like that Winchester 6.5 ball powder? That is one of the powders I can find pretty regularly in my area but have never loaded with it.