Hear is a really cool trick that gives you 260 rounds for duel needlers.
Go to Battle Creek switch your weapon for a needler, then grab a magnum as your 2nd weapon and duel wield other needler, go to the other side fo the map and swap the magnum for the other needler. Now you should have three needlers. Just keep getting ammo and soon youíll be unstoppable. Note: Iím sorry I used the word 'needler' so much.