This is a quick easy glitch so you can use the Wing Shooter as much as you like and not worry amount running out of ammo!

1) Play as Leon in the campaign.
2) Run the ammo down till you have a few bullets in the last magazine.
3) Aim down the sights with LT.
4) Whilst aiming down the site, press Y to switch to duel wield.
5) Switch back to the Wing Shooter.
6) You should now have full ammo.
7) Repeat this every time you are running low an ammunition.