compression/velocity

[Kurt]

I shoot year round and during the winter shooting the old Goex powder that needed some heavy compression I saw a lot of unburned powder on top of the snow that made me wonder what the gain in velocity was per compression. The velocity increased with every .100" of compression but at a point as the compression increased the velocity increase started to drop but the bore had more shine, but the velocity never stopped increasing.
This took me to another thought what is the increase of unburned powder from light compression to heavy compression.
I went to a carpet installer and picked up a 12' cardboard tube the carpet roll is on and I split that tube and taped it back together and taped several layers of cloth over the far end and shot into that tube to collect the unburned powder. I was amazed just how much unburned powder in chunks I found. It was mot bad powder because when I was done weighing it I set a match to it and it flashed up.
This also made me think that the unburned compressed powder chunk up front is what whipped the fouling out and made it look like a clean burn.
If you look at the picture below, that powder is compressed .300" and it is solid up front.