Deadfall Adventures

Before you start a multiplayer match or on the general multiplayer menu of the game, there is a customizaiton option. Go into it and select a custom loadout. Change any of its weapons to the ones you desire. and change the primary weapon. and change the secondary weapon. This feature allows you to obtain a loadout with just the right qualitative advantages and trade offs. Once you're done, select this loadout to use during a multiplayer match. You'll unlock the DIY achievement once the match is over.