Crown paintball barrels: "How to crown a paintball gun barrel without a lathe

I crowned the Taso SS Pro barrel on my Tippmann .68 Carbine and got rid of the flyers that the gun was throwing 20% of the time. The barrel had minor visible imperfections on the crown. I have access to a lathe that I have used to crown Firearm barrels, but it is a lot of trouble. I thought I would try something that anyone can do.

This method won't work if you cut off a barrel with a hacksaw. You would have to use a lathe on that. But I think it will suffice on most barrels.

I bought a 1' diameter SS ball Bearing from Small Parts, Inc. and some 120 Grit valve Grinding Compound from a local Auto Parts store. (Small parts has the compound too, if you want to get everything from the same place). I applied liberal amounts of the compound to the bearing, and holding the barrel in a vertical position, rotated the ball on the crown of the barrel. Don't keep the ball in the same position, but roll the ball as you grind. You should use the entire surface of the ball during the grinding session. Since you are doing all of this by hand, rotate the barrel at intervals also. This will minimize uneven wear from the handheld process. After about 5 minutes of sporadic grinding (it makes your hand hurt), I had a nice even gray grind pattern just under 1\16' wide. "