I've spent the last few months working up a load for a 284 Winchester with H4350. I am shooting 150 grain Sierra TGK with Peterson brass and Federal 210M primers. I recently finished off a pound of H4350 and opened a new 8lb container. I was fine tuning 3 well known loads at 53.5, 53.6, and 53.7 grains which should have produced rough average velocities of 2890, 2900, and 2910 FPS per my extensive previous testing. Instead what I recorded was 53.5 grains pushing close to 3000+ FPS. After I shot 2 rounds of the 53.6 grain load and recorded over 3000 FPS I quit. The cases and gun were both showing signs of pressure which is expected when running at those velocities. First thing when I got home I checked my scale. The test weights proved true so I loaded 2 more rounds at 53.5 grains and headed back to the range (conveniently 2 minutes from home) and recorded the same results; velocities near or above 3000 FPS. I then loaded up 20 rounds, 2 at each charge, working in 0.1 grain increments starting at 51.4 grains and ending at 52.3 grains. The velocities for 51.9, 52, and 52.1 grains (2885, 2913, 2923; 2 shot avg FPS) were close to what I was expecting with the previous lot of powder using 53.5, 53.6, and 53.7 grains. Nothing else except the new powder lot and outside temperature (it is cooler now than when I first started testing) has changed in my reloading process. This amount of variation seems insane to me. Has anyone else experienced anything like this, particularly with H4350? I normally use VV and am considering switching back to N160 if I can find some.