While cleaning my AR I seen deposits of powder/lead/dust whatever right where the locking lugs are located on the upper. No matter what I use brush/qtip I can't seem to get it all out. What type of brush do you guys use for this. I have only had my AR a short while and have yet to really disassemble it all the way down. I wasn't planning on doing it till I got a vise, and the needed wrench. And downloaded the video as to have another source other than the crappy military issue manual that came with it.