I found with my DSG if I didn't pump it very quickly I would often get two rounds in the chamber due to the spring feed.
you could always pump an extra ball or two in if you wanted...
I did that by accident once. ended up shooting 5 rounds down range. Made me laugh so hard I go shot out!
Not recommended though, you cant aim them and the velocity is not great so you are likely to get a lot of bounces...
My business card says "Your in luck, I do two things..."