I picked up some 2013 Swiss 1-1/2 at our last match from a friend who is no longer able to shoot. I found that comparing equal volumes of my last powder to this 2013 powder, it was 4 grs less by wt. than my old powder. I don't have a chrony so was wondering if I'll see a 25-30 fps drop in velocity with this powder. Reason I ask, is I'm shooting my 45-70 in 2 weeks at Lodi and I consider it marginal at times at the longer distances. It shot quite well on practice day at our LR match in Harris with 70 grs of my old Swiss.
Is the energy in the mass of the powder or the volume or isn't it a big deal??