Methods and apparatus are described for safety apparatuses for weapons. An example safety apparatus includes an interchangeable barrel and a safety mechanism. The safety mechanism can be moved between an open position that corresponds to an unlocked position and a closed position that corresponds to a locked position. The safety mechanism includes a feeder cover that is part of cartridge loading equipment that supplies cartridges to the weapon. The feeder cover includes a locking mechanism that engages with a barrel locking device and prevents the feeder cover from entering the closed position if the interchangeable barrel is not coupled to the weapon via the barrel locking device. Further, the unlocked position prevents the weapon from being fired and the locked position allows the weapon to be fired. Additionally, the barrel locking device couples the interchangeable barrel to the weapon and wherein the barrel locking device interacts with a safety mechanism and prevents the safety mechanism from entering the locked position if the interchangeable barrel is not coupled to the weapon via the barrel locking device.