Simply display the inventory screen and combine ammo manually with your weapon. This causes weapons like shotguns to reload quicker than the normal method. You can also use this trick while climbing ladders or jumping.
Reload your weapon when the melee option appears, then start the melee sequence. Your weapon will be instantly reloaded.
Easy completion in "Mercenaries mode":Note: Two players are required. Have one of the players quickly go for the time bonuses instead of getting too caught up with enemies--get about five minutes worth of time. If you can, collect the combo time to rack up some serious points. Then, meet up with your partner and find a place to hold out and accumulate points. Every level plays out differently and can be tougher than others with this strategy. Try making a route for each time bonus. Note: If you are playing on "Public Assembly" or "Ship Deck", avoid a hiding location. Instead, move and kill or else the chainsaw Manjinis or executioner will catch up to you and kill you.