The Nerf Rival blasters can fire foam balls at up to 70 miles per hour. Pretty awesome right out of the box. Impressive, but not enough for YouTube’s Captain Xavier, who modded his Nerf Rival with a spinning feeder and a 2,000-shot backpack. If you do the math, that is about 20 foam balls for every second. If this heavily modded Nerf Rival has the trigger held down, it will devour 2,000 rounds in just over a minute and a half. Video of Captain Xavier and his crazy Nerf gun after the break.