I guess I could have started a separate thread, but this question is closely related to the original post.
I have a new 9mm pistol and am starting to work up a load for it. The bullets I am using are Berry's 124-grain heavy plated HBFPs and I would like to use Universal powder. I can find data for those bullets but not with that powder, and vice versa. The shortest COL listed for these bullets is 1.060", but in order to plunk in my barrel they need to be seated to 1.020". The lowest starting charge for a 124-grain bullet I can find is 3.5 grains. That is the starting charge Lyman #50 indicates for a Hornady HP/XTP, also seated to 1.060".
My question is this: is it safe to start my load development at 3.5 grains seating the bullets to 1.020", or is that 0.040" difference enough to increase the pressure to a dangerous level? GRT does not have the Berry's bullet in its library, but substituting the 124-grain Hornady shows a pressure difference of 5100 psi between the two seating depths. Max pressure at 1.020" is shown as 27k, 7k below SAAMI max, but that's not for the bullet I'm using.
I think I'm probably on safe ground, but it's always good to ask and see if there's something I'm missing.