When playing MGS V I tried fucking around with it and got some really weird guns like

A pistol with a grenade launcher barrel and a scoped shotgun on top of it, fairly normal

It has two triggers so you can fire two shots at the same time and kill the same person twice

A pistol with a grenade launcher attached to it with a rocket launcher attached to the grenade launcher

The pistol was redundant so I replaced it with…well it seems to be a scope that is actually a gun