You'll get a legendary with three of the vault symbols. Don't even try though, the odds are fukking impossible. It's better to just farm. Wait till you're at max level to farm for legendaries though, because even legendaries fukking suck when enemies are 5 levels higher than the gun.
The game is addictive as shyt.
Stop now, or you're not going to bed tonight
(also if you were on PC, I'd power level you up to like level 50 in a few hours
You just gotta find somebody willing to spend the time to help you out [power leveling is not at all fun for the person that has the much higher level than you])