Ambush the Train | Main Missions GUN Guide

Get on the horse and move behind Clay. When you'll reach the tunnel, take the TNT barrel from the cart and place it under the rocky boulder [1]. Do the same with two other barrels and move forward. You should arrive near the train (firefight), so take down all defenders [2], and then take care of gunmen on the horses.

Return with Clay to your trap and place the fourth explosive barrel near the rock. Go up, aim at the TNT [1] and patiently wait, until the detonation sign will appear (the meter on the left side of the screen). The train should stop. Eliminate all guards [2], who will run from the carriages. Mission complete.