I used that stuff for 2 entire restorations before they started putting the "coal slag" on the bag. Ingenious on their part...charging people to take your refuse. Given that coal is high in lead and mercury, I doubt that stuff is good for our health. Thus their having to finally add the disclaimer! No sand is great for our health, but I bet beach sand would be much better than slag?!?
I have never had to remove the bullets from the harness to pass them through the stator. The bullets are staggered so they don't bunch up together. I did use wd40 or wire pulling lube and was then able to push the wires through the tube about 1/2" at a push. I made sure there were no twists, as any twist will tend to expand the diameter of the bundle slightly...which is significant when you have so little room to spare..