These Balls were pretty cheap, only $18.50 after S & H (500). I've used two different batches and out of a thousand only 1 of em broke in the barrel and most broke on target
There is a huge seam through the ball, which in my opinion made the balls look rather cheap. A lot of them curved to the right pretty bad. They also seemed to be inconsistant in size. When I had the barrel off of my gun checking to see how the balls fit, some were easy to blow out of the barrel, some would get stuck and have to be broke, and other were pretty tight but could be pushed out with a squeegee.
I don't know maybe it was my barrel....I called nelson before buying them and they said the balls were small bore. They are decent for the money, about as good as superswirls