Was the seating depth the same? if you seated deeper and the volume was decreased you can gain velocity also if you seat longer but you're in the lands( some people say jam) that can increase pressure and velocity as well hope this helps.
I had the same thing happen with my .308 and 155 grain Noslers . 46.5 grains of Varget produced more velocity than 47.0 but the 47.0 load was more accurate . I have a second batch ready to go test again and see how it works out on the second go round .