"it will wreck a Lee PPM"
a few grains got into the rotor, and scratched the crap out of it, causing it to bind.
Cases were bulged just ahead of the rim, where the die would not reach to resize them. They would not slip freely into or out of the chambers, after resizing.
Uhm... Define "precipitiously"...
In the work-up, 14.5 gr was the last point that did not cause the cases to bulge at the base, and gave around 1100f/sec with a 158gr XTP. 15.0 gr bulged the case heads slightly, 15.6 such that extraction was difficult.
14.5 gr of 2400 with a standard small pistol primer gave a velocity that averaged just under 1250, with less flash/blast, a lower SD, and did not bulge the base of the case at all.
Same bullet (158gr XTP), same gun (Colt Trooper MkIII, 6"), same chronograph on the same day .... same everthing but the powder and the primer.
I did load up 100 rounds with 15.3gr of H110 just for giggles and took them to an IDPA mini-match ..... stage started with first target 6" from the shooter ..... on the signal, shooter was to step back and draw and shoot from retention ..... 1 arrived late and there were 20+ shooters that had holed the center of the target pretty good, such that the thing was held together as much by pasters as by cardboard ...... at the beep, I stepped back and to the side and fired twice, blowing 2 fist sized holes in the -0 area, and a shower of smoking cardboard-and-paster confetti out behind the target. The front half of the stage was poorly lit, so the muzzle flashes were dazzling, and the gun was loud enough to cause onlookers to ask what caliber of hand cannon I was carting around..... most of the "serious" competitors were using wonder nines or 1911's with mouse fart loads .....