The Railgun needs work...

http://xboxdvr.com/gamer/II%20Jonny%208oy%20II/video/15011309

Two hits, no kill

That has more to do with latency issues than anything. You are most likely playing on a server that’s closer to the guy you’re shooting causing a few hundred milliseconds delay and causing this to happen. You’re seeing a hit, the other guy (and the server) would probably show you just missing the guy by an inch.