Well I would try to blame it on ball hop, but it shouldn't be getting any since it's force feed. Where is all the paint from the broken balls at. If it's in the feedneck and chamber, then it's probably the bolt breaking them. If the paint is all over the inside of your hopper then it is breaking in the hopper, though I wouldn't know why.
This has come up before, and I think the solution was something to do with the length of the feedneck. Have you cut yours down at all? I believe that the time I saw this before, the person had to raise their hopper up in the feedneck some. What you are getting is ball crush where the drive cone is smashing the balls at the top of the feedneck.
Think of it like this (simplified for visualization purposes):
A paintball is one inch in diameter. The length from the top of the bolt to the part of the raceway that the drivecone passes through is 5 1/2 inches. 5 paintballs will sit in there just fine, but won't touch the drive cone, so another paintball tries to sit in there and *splat*. Get's chopped by that little groove inside that the paddles of the drive cone pass through. Solution: either a half inch longer or half inch shorter feedneck.
Keep in mind those measurements weren't real, just examples.