In the 70's there wer a lot of 'fines' in the GO and other powders - dusty, they were. Today, I've not seen this as a problem with GOEX. To me, it looks like excellently, clean, hard shiny grains of powder with litterally no dust or 'fines'. It surely shoots well for me and I do use a mic.
It also shoots OK in my Sharps, is 1" for 5 shots at 109yards using apertures is OK. I haven't done any long range shooting with it to far, though. We will be this coming summer with our new 1,065 meter range, and will see then if we need to sift the powder.
As I think I have posted before. When Goex was making powder at Moosic they were using ground water contaminated with bacteria that EAT sulfur. As soon as the water was added to the mix they went to work and ate at the finished powder until the oxygen level would drop in a sealed can. The interesting part was many cans came with loose lids.... So when new powder arrived first thing all the lids got tightened.
There were good lots and lots that were useless and simple would not produce accuracy in a BPCR and every new lot required new load development.
Some lots were so dusty that 25% of the powder was unusable.
This was all too apparent when using a drop tube to load cartridges. When I got down in the can far enough to get a layer of powder dust on top the the charge in the case, the dust fell slower than the grains, I changed powder cans.
I scrapped a lot of powder this way.
People shooting MLs might not notice the dust as easily.
A friend who posts here and lived in Easter PA would tell me what lots to buy based on the rainfall. Heavy rain during a month made for better powder since it diluted the bug count.
This problem went away with the move to Minden, cleaner water. So the powder immediately improved. There were other things that improved the powder since Moosic as well.
Dan