7.0 grains, definite winner.
Zero FTF or any other problems across the whole set. The 6.0 gr loads went through the paper sideways, I'm assuming too slow to get a good spin in the rifling, and some of the loads grouped okay but had 1-2 inexplicable flyers several inches away from the other impact points.
Figure I'll load up a bunch of these at 7.0gr and give them a more thorough run. Recoil and muzzle blast was nice and mild, a little more than the .44 specials we tried last month, and certainly within the range that'll be comfortable for both of us to practice with.