Take the NF spring out of there. It simply doesn't belong. Either that, or you have your batteries backwards.
Then how is it that other people get a spring in there? Don't tell me you need to up the voltage because I've been told it works with stock voltage, just a lower ROF. And no, I don't have my batteries backwards XD
I agree with what Talio said, but I have something to add. DON'T BE STUPID. You saw the crap on the news. One of the main points of the video was that it was dangerous because children were putting thumbtacks in darts. Seriously? SERIOUSLY? THAT is the kind of crap that gets us in trouble, not as much the wars. Thumbtacks or sewing needles can stay out of Nerf, thank you. Before you go putting something on Youtube or bringing it to a war, think: if I get caught with this, will it make Nerfers as a whole look like they are putting kids in danger? If the answer is yes, then, oh, I don't know... DON'T DO IT!
How would this do if you took that stupid ass foam guy off, jammed some (insert barrel material here) down the front and shot a stefan from it? Jesus christ, titan-ish.