There's not a gun I currently or formerly own that I hate, thankfully. However, the one gun I've fired that I absolutely do not enjoy shooting is my cousin's old Mosin Nagant. It's everything I dislike in a gun: a heavy, creepy trigger; non-adjustable (left-right, at least) iron sights that send the bullets way to the left even at 25 and 50 yards; a flat buttplate that makes the gun recoil uncomfortably; and a difficult bolt that has a tendency to get stuck both while open and closed.