A magazine well insert prevents contaminants from entering the magazine well of a pistol or a rifle. The magazine well insert provides a visual indication that the weapon does not have a magazine installed, thereby enhancing weapons safety. The magazine well insert of the present invention protects the weapon's magazine well from becoming contaminated with sand and other debris by sealing the magazine well with a block, for example, a plastic or metal block, that has an o-ring or other sealing device adapted to be positioned at the opening of the magazine well. The magazine well insert may be used in two different configurations, a first configuration that allow normal operation of the weapon's action or a second configuration that blocks the action of the weapon. The magazine well insert may be hollow with a removable sliding base to provide for storage in an interior portion thereof.