The narrower the screen range, to a small extent you get higher void space and thus lower overall density. My meshes are 15 (kitchen sieve), 20, 40, 60, 100. I need to get a 30 and a 50 to make the duplicate size ranges to commercial.I also did some more screening. to only gather the grains between 30 and 40 mesh. This isn't to far from the mark after all, if I push it up slightly from 1.64 density to 1.7 I might be there...then again, maybe this is where I want to be.
To try and raise the bulk density I took my 20#-40# fraction, scooped a bit off the 60# (maybe 10%) and add it back to simulate a 20#-50# range of FFFg.