Similar for me; my '15' is a kitchen sieve and what stays on it gets reground. Then
20
40
60
100
Fitted pan for fines.
I am getting apparently good density in pucks of 1.77-1.80.
But bulk density of my powder is 88 to 90 grains in a measure set to 100 grains. Swiss 3F gave me 102 grains in that 100gn measure.
I believe that the overlapping sieve size range (ie 15-30# for FF, 20-50# for FFF, 40-100# FFFF) would increase bulk density. Also that rounding the grains and graphiting them would reduce friction in their flow and settle them more easily which again would increase bulk density.
Charges in my muzzleloaders are doing a great job so I am pretty satisfied. The guys at my club have tested it and compare it to Swiss!
The only reason for doing more work to get high density is for cartridge BP.
mmb617, I too am having to reprocess 4F to get more 2F as I just don't use 4F much.