I am assuming those are around 180 grains or so? At 80gr 2f Goex out of a 22 inch barrel (I estimated barrel length from the picture) you should be getting 1700-1750 at the muzzle. I personally think you went goofy from 50 to 100. It's ballistically impossible with that muzzle velocity to drop 12 inches from 50 to 100. Unless you were shooting into around 20mph of wind head on. Either your hold was off or you goofed on sight adjustment. But if you were getting that muzzle velocity for both ranges you couldn't have been 12 inches low between them through any velocity loss. Maybe you were getting a better seal during your 50 yard shoot and switched something when you went to 100? Losing a ton of velocity at the muzzle.