YouTuber Out of Darts recently took a NERF Rival Zeus blaster (which is pretty awesome right out of the box) and added a few upgrades that make it unmatched in terms of raw firepower.
In the videos below, you will see how he modified the gun to fire on either a 3-round burst or full-auto with 56 rounds, 108 rounds and, finally, a 270 round design using a backpack loader (that could be modified further to hold thousands of rounds).
Here are the basics on Out of Dart’s customizations:
Here he shows how he increased the Zeus’ capacity from 56 to 108:
And here’s a video on how Out of Darts added select-fire capabilities to his Zeus:
Finally, the Nerf Rival Proton Pack design: