Westerado: Double Barreled

This can be a bit tricky. The key is to first focus on the bandits that don't pull a gun. They are the ones going after the packages.

Remember that you have to cock the weapon prior to each time you shoot, so when shooting a bandit, go ahead an pull twice in a row so that you are cocked and ready to fire on the next bandit. After that shoot the bandit(s) with his weapon drawn and fully reload between waves.

After about four waves, they will stop coming and you will get the achievement.

Note: ElQuaNarXBOX mentioned that hiring the Beefhead Bulls to join you may help.

I found a nice little trick for this. Stay to the left of the screen and shoot the guys as they ride past you.

You normally have no chance when they get close to the wagon, but shooting from behind gives you more time to react.

For the record I found the Beefhead Bulls to be pretty useless so dont stress about hiring them.