Avoiding them: Bore your paint correctly, store your paint properly, keep your gun lubed, and keep that barrel clean
NONE. Hammerhead and old school snort barrels would say "self cleaning" neither worked. As for freak barrels, I've had paint actually push around the outside of the insert from shooting through breaks... You won't get an accurate shot trying to push through a break, no matter what barrel you have.
Get quick with that squeegee!!