i have a stock barrell and nothing is wrong with it yet
Not much. In my gun they rarely broke.
I bought them from a dealer and they were expensive. My friends were using a Viewloader Genesis and a Pirahana G3. The balls broke in their guns about every 50 shots. They broke in the speedloaders, and our hoppers. Very unaccurate.
Don't waste your money on these balls. Your better off with Brass Eagle.