Mossberg 500

Mossberg 590A1
Mossberg 590A1 in 12 gauge with heat shield and bayonet lug
Type	Shotgun
Place of origin	United States
Service history
In service	1960–present
Used by	See Users
Wars	Gulf War Iraq War Operation Enduring Freedom
Production history
Designer	Oscar Frederick Mossberg
Designed	1960
Manufacturer	O.F. Mossberg & Sons
Produced	1960–present
Specifications
Weight	5.5 lb (2.5 kg) to 7.5 (3.4 kg) empty
Length	varies with model
Barrel length	14 to 30 inches (350 to 762 mm)
Caliber	12 gauge, 20 gauge, and .410 bore
Action	pump action
Muzzle velocity	403 m/s (1,325 ft/s) for 12-gauge, 2 3⁄4", 00 buckshot load 475 m/s (1,560 ft/s) for 12-gauge 437-grain rifled slug
Effective firing range	40 m
Maximum firing range	50 m for shot, 300 m for slugs
Feed system	varies, 5+1 to 8+1 rounds; internal tube magazine
Sights	varies

Mossberg 500 is a series of pump action shotguns manufactured by O.F. Mossberg & Sons. The 500 series comprises widely varying models of hammerless repeaters, all of which share the same basic receiver and action, but differ in bore size, barrel length, choke options, magazine capacity, and forearm materials. Model numbers included in the 500 series are the 500, 505, 510, 535, and 590.

Introduced in 1960, all model 500s are based on the same basic concept designed by Carl Benson. Originally using a single action bar, that was known to bind and even break, this was changed to dual action bars in 1970, following the expiration of Remington's patent on the double action bar design. A single large locking lug is used to secure the breech. The magazine tube is located below the barrel, and is screwed into the receiver. The slide release is located to the left rear of the trigger guard, and the safety is located on the upper rear of the receiver (often called a "tang safety").

Sights vary from model to model, from simple bead sight to a receiver mounted ghost ring or an integrated base for a telescopic sight. Most models come with the receiver drilled and tapped for the installation of a rear sight or a scope base. The factory scope base is attached to the barrel via a cantilever-type mount, which places the scope over the receiver but keeps it with the barrel if the barrel is removed.

Intended for use in harsh and dirty conditions, such as waterfowl hunting or combat, the Model 500 series is designed to be easy to clean and maintain. All Model 500s feature interchangeable barrels (given a particular gun's magazine capacity—a barrel designed for a five-shot tube will not fit a gun with a seven-shot tube), which may be removed without the use of tools, by loosening a screw on the end of the magazine tube, allowing the barrel to be removed.