Tinker,
I'm intending to run some smokeless first, just to compare to the other 12 bore bullets I have. Maybe black powder one day, just haven't got that keen just yet.
I'm going to fill the grooves with LBT Blue, which is what I put in the grooves of the CBE bullet, SPG might also get a trial as well, and I haven't overlooked Liquid Alox either. Lubing them will be a slow process and a real pain I'm thinking. I usually extrude a ribbon out of my grease cookie extruder, cut about a 7-8mm wide section, roll it into a sausage shape, lay it in the groove and flatten it out as best I can, then run through a push through sizer in the press, sized to 0.730, it just smoothes out the lube.
Smaller grooves and more bearing area might have been better on this one, but we'll see.
Going to load them tonight to try at our upcoming Big Game Target shoot in a couple of weekends time.
The lead used is exactly the same as what I cast Fatboy's 404 bullets out of, wheelweights with a splash of Linotype and a touch of pure tin as well, and maybe a little pinch of "eye of newt"

The centre of each bullet cast, as you can see is a bit frosty looking, I had to cast these pretty hot to stop the nose solidifying too much before I finished the pour, this is from a bottom pour pot. I think ladle cast might have to be a priority on something this big.

I'll post a photo of a lubed bullet and a loaded round later.

Regards,
David.