This is a video of Adam Savage completing a one-day modification of a NERF Rival Nemesis ball blaster to allow for a 1,000 round magazine on top. The original blaster only holds 100 rounds, so this one is 10X original capacity. He also adds a bipod, red-dot scope, and custom paint job. Impressive, but it looks like you still need to shake the gun a lot while shooting to make sure the balls load into the firing chamber. I feel like that's a fundamental design flaw. Nobody wants their balls getting stuck, especially not in the wide-mouth of their roommate's gym water bottle. "Um, what?" Start buying your own protein powder, Derek.
Keep going for the video but skip to 34:40 if you don't want to see a bunch of plastic cutting and just want to see the thing being fired at people in inflatable dinosaur costumes.
Thanks to K Diddie, who agrees the more the merrier is not always the case when it comes to balls.