No idea how to drill/tap. And wouldn't that get in the way of the firing/paintball path? The body is not very thick. Yeah, it might be a waste for the body, but the easiest method. I have no intention of using this with a hopper, but if I ever do change my mind replacement bodies are pretty inexpensive.
Thanks for the spring info Tony, shipping is 5$, so not terrible. It should feed 10-12 rounds? If I'm not mistaken.