I think the real fairy dust for this cartridge and a number of others like it is RL26. If I could find a few pounds of that I'd be all over it.Supposedly it's doable… I'm gonna do some more digging a find out for sure. I'd like to find enough of the fairy dust (H1000) to make it worth it. I find 1lb containers once every 4-5 months but that would take ages to get enough to last.
I'll probably try to make some of that brass. Looks like it needs quite a bit of trimming, I wonder if the necks need turned too.
I just found some more data, Hogdgon has StaBall HD listed for the 270 WSM, along with Retumbo. StaBall has a starting load 2gr more than Retumbo.