The Mossberg 500 shotgun is one of the most popular security/tactical shotguns in use today. Mossberg also produces this line of shotguns for hunting and target purposes. You can quickly remove the stock on a Mossberg 500 to either reconfigure the shotgun or to simply change the stock. Pistol grips are also available for the Mossberg 500. However, before you replace the shotgun’s standard stock with a pistol grip, check your local laws to ensure that the pistol grip configuration is legal in your area.
Check that the shotgun is unloaded by placing the safety and the "on" position, pressing in the slide release (located next to the trigger housing), and opening the action by pulling back on the fore-grip.
Use a standard size Philips head screwdriver to remove the screws holding the butt-plate (the rubber pad on the end of the stock) in position and remove the butt-plate.
Look down the exposed hole on the rear of the stock and determine the bolt head configuration (some Mossberg models have a slotted head and some utilize a 1/2-inch hex head).
Use your standard screwdriver or your Allen wrench (depending on which configuration you found) and remove the bolt by rotating it counter-clockwise. The stock will now come off the receiver.