a gun body including a gun head, a main part, a trigger part and a gun handle, the gun head having a muzzle, one end of the main part being connected to the gun head, the gun handle being connected to the main part and away from one side of the gun head, the trigger part being connected to the main part and the gun handle, and an accommodating groove being created between the trigger part and the gun head;

a holster body including an accommodating space and a hole, the accommodating space being configured through both ends of the holster body along a first direction, the accommodating space accommodating the gun head and the trigger part, and the hole being located on one side of the accommodating space;

a limiting device disposed in the hole, the limiting device including a buffer block, the buffer block extending from the hole to the accommodating space along a second direction, wherein, when the buffer block is in a first position, the buffer block extends from a surface of the accommodating space at a first distance;

wherein, when the gun body is inserted into the holster body, the muzzle is inserted into the holster body from a first side of the accommodating space along a path, and one end of the gun head abuts the buffer block, so that the buffer block is located on a second position; and when the muzzle moves to a second side of the accommodating space, the holster body covers the gun head and the trigger part, and the buffer block is located in the accommodating groove and restricts the gun body from moving;

wherein the limiting device further comprises a box body, an adjuster and a spring, the box body having a groove to which a third end of the adjuster is connected while one end of the spring is connected to a fourth end of the adjuster, and the other end of the spring is connected to the buffer block, so that the buffer block can be located at the first position or the second position via the spring;

wherein the limiting device further includes an adjusting screw, the adjusting screw being arranged in a through hole of the groove, and one end of the adjusting screw abutting the fourth end of the adjuster;

wherein, when the adjusting screw performs a rotational displacement movement through the through hole, the adjusting screw performs a linear displacement movement along the second direction, so that the adjuster performs the linear displacement movement.