The 340 grain Lee 45-70 bullet (336 grains in hard alloy) in my Ruger #1 is very accurate with Unique. 14.0 grains gives 1" groups at 50 yards. I'm going to try more to boost the power a little, but it makes for a very nice medium load.

I'm using a similar bullet, the Lytman 457122HP, the hollowpoint gould-style design, which casts out at 342 grains from my mould using wheelweights. I have shot this bullet up past 2200 FPS using a heat-treated bullet, and inverted gascheck over the powder, and a charge of Re7. It is a MOA load for three-shot groups, and would no doubt be a real killer! I heat-treat only the rear 2/3 of the bullet, leaving the nose portion soft so it'll expand.