Makes the double barrel shotgun behave more realistically. Normally a double barrel has two triggers, one for each barrel. And if you so chose (and dont mind hurting your shoulder a bit) you could pull both triggers at once, and fire both shots. So thats what i did. Now the double barrel will fire one round if you pull the trigger, but hold the trigger for half a second and it'll fire both. This was requested by godsavant on Reddit. Thanks to him for the idea! 

Future plans: To add a receiver upgrade to make this a choice as opposed to default behavior.