Originally Posted by Spock
Sometimes a ballpoint needle will catch on some brands of pins. Don't know why and haven't put them under the microscope for a better look.
My guess would be the ball point needles have a bigger surface area at the point than the sharps. The sharps would push the pin aside unless you whack it dead center at high speed. The ball points are made for knits. They are used to push through the fiber instead of weakening it by piercing and possibly cutting the fiber. I would not use a ball point needle unless I was using a knit. I especially would not use one on silnylon because it would be more apt to push the fabric into the throat plate and leave a bigger whole than a sharp.