I recently bought a jug of surplus SR4759 for a very good price. About 1/3 of what the cannister powder costs. Only thing is, I've noticed that there is a lot of contamination in the powder. Small brass flecks and granules of what look like carbon. I would guess this powder came from disassembled military rounds. That would explain the brass but not the carbon(?) granules.
I've found that I can clean this powder by pouring it out, about a cup at a time, onto a cafeteria tray, then tilting the tray and letting the good powder roll down the tilted tray. The brass and granules, not being round, don't roll down the tray so they seperate out and I can remove them. I get about a teaspoon of contaminant out of each cup of powder. The granules do not burn so I have no idea what they are.
Has anyone experienced this in a surplus powder, and do you think it is harmful to my bore to fire powder with brass flecks in it? It seems that my cleaning process is very effective so I'm not too concerned about the harmful effects, but I was just wondering. The powder seems to perform as well as the cannister stuff.

There is an old saying, "You get what you pay for."

As for the "black stuff", it is probably dried asphalt sealant.

------------------
http://stevespages.com/page8.htm

Geez, and I thought the guys that weigh cases and fill them full of water and "true" their flash holes had a lot of time on their hands......... Sorting smokeless powder. Wow, that's got to the the ultimate dead-end job for a rainy day. I think I'd load some up and shoot it and see if it adversely affected my rifle -if anything, the brass and sealant may make it harder to clean. If the results were unacceptable, I'd sprinkle the stuff on the lawn and consider it a lesson learnt.