100 Rounds of Bertram Brass are in from Defensive Edge. When I measured the shoulders with the Hornady .420 Headspace Gauge I found them to have 0.009" of variance, ranging from 2.456" to 2.465". I would like to be able to do some initial load development without having to fireform custom brass that cost $3.15 a piece, but am afraid that the variance in the shoulder could skew my results on powder charge and seating depth. Am I being too picky here? What are some recommendations? Begin load development with longer shoulder brass, shorter shoulder brass or fireform everything first (>$1 a shot + wasted time)?