BarryAllen

I think your problem is simple, barrel too long. I'm not totally sure what the optimum barrel length on a bbb is, but mine gets pretty good ranges at about 3 inches. Try taking it down to 5 or 6 and see what kind of ranges you get then. Optimal length seems to make the BBB get about 70' or so, I believe.

Did a little surfing on his site, listed in his profile.
Didn't see a longshot in his nerf gun gallery, but a couple of interesting.. if not weird and cumbersome integrations.

Here's that gallery.
Guns

He's also got another gallery of him posing with his vulcan, I'd like to see a better shot of that paint job.

Although, as someone as someone who has done web design work, his website makes me want to cry vomit.

Whatever, he gave the link of a web services company, but certainly not his own site. At least it appears to be a real nerfer here and not some spammer.

Good job.

It's funny, I'm watching Family Guy, and Stewie is doing his thing, and I'm reading your post. A little surreal.

Anyway, this gives me an idea for a misc tips and tricks thread. Hint hint to someone more experienced. Screws would obviously be a big topic. Glad to hear this method worked for you.

The gun is NF ex 3 and it is the central screw under the barrel between it and the light, and i also can't get on off on the handle. So the saw will not work in the central one however i will try it on the other screw in the handle.
Sidewayz

Here's a thought, cut up your gun. Do a minimization mod on it, there are many on the haven of course. Cut that screw right outta there in that mod. Shouldn't be too hard. That might just be the easiest solution to the problem, especially if you don't care about all the extraneous cosmetics.

There's a lot of good advice in this thread already. Superglue a cheap screwdriver in there, wait for it to thoroughly dry, then get that sucker out of there. Firecracker would work - but you can't get one it seems. Dremel or drilling works. On several casings, including Nerf guns, I've eventually just brute-forced it open, prying it apart until the screw support snaps. Or you could go the more finessed way and get a razor saw between the shell halves and saw the screw support that way. The real solution to all this is good tools, I've been meaning to get a ratchet/screwdriver set that can access smaller holes.

Of course, with as much work as I imagine you may have done, I think you could have stripped a screw. Is it at all possible you've been using a poorly sized screwdriver? Also, what kind of gun is this and where is the screw?

And by the way, the Haven seems to be kind to you, no one has yet called you on not searching. Screw problems are nothing new, of course. Here's a few of the more recent threads.

Stupid Freking Screw
The Screw That Won't Unscrew!
Overly Tight Screw Problem