A friend of mine is convinced that Al GCs, when pushed to high velocities (>2000 fps) will leave behind fouling in the barrel, and ruin accuracy. Have you guys ever seen anything like this? The only accuracy testing I've done with Al GCs has been in the 1500-1900 fps range, and I could detect no difference whatsoever between the Cu and Al GCs. I have some .30 caliber Al GCs, and have planned to do a comparison between Cu and Al using a Husqvarna .30-06 (1 in 12" twist) and a pet load at 2150 fps, but that project is a little ways down on the "Things To Do" list. It seems that you guys like Al GCs, what about at higher velocities?