The Mossberg 500 is a shotgun manufactured by O.F. Mossberg & Sons. Rather than a single model, the 500 is really a series of widely varying hammerless, pump action repeaters, all of which share the same basic receiver and action, but differ in bore size, barrel length, choke options, magazine capacity, and "furniture" (stock and forearm) materials. Other model numbers included in the 500 series are the 590, 505, and 535.

Basic Features

Introduced in 1961, all model 500s are based on the same basic design. Originally using a single action bar this was changed to dual action bars in 1970, which are (at least in theory) less likely to bind than a single 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 505 series is designed to be easy to clean and maintain. All Model 505s feature interchangeable barrels (given a particular gun's mag capacity; a barrel designed for a 5-shot tube will not fit a gun with a 7-shot tube) which may be removed without the use of tools, by loosening a screw on the end of the magazine tube, which allows the barrel to be removed. The bolt locks into a locking lug located on the top of the barrel, ensuring a solid bolt-to-barrel connection and not relying on the receiver for any locking strength.

The trigger assembly, which includes the trigger, hammer, sear, and trigger body with guard, can be removed by pushing out one retaining pin and pulling downwards on the guard (if a pistol grip is installed, it usually must be removed first as virtually all such grips obstruct the removal of the trigger body). The elevator can be removed by squeezing the sides together, freeing the pivot pins from the receiver. The forend can then be moved to the rear, allowing the bolt and bolt carrier to drop out, and then the forend can be removed by moving it forward. The cartridge stop and interrupter will then fall free, leaving just the ejector and the safety in the receiver, held in by screws. The magazine spring and follower may be removed by unscrewing the tube from the receiver (this may be difficult on some new 505s).

This level of field stripping is sufficient to allow all components to be cleaned.

Model 500 variants

The Model 500 is available in many variants, for a wide variety of applications. The ease of changing barrels on the Model 500 means that a single shotgun may be equipped by the owner with a number of different barrels, each for a different purpose. As sold, the Model 500 is generally classed into two broad categories: field models and special purpose models.

Field models

Field models are the basic sporting models. They are available with a variety of barrel lengths and finishes, and may be set up for waterfowl hunting, upland game hunting, turkey hunting, or shooting slugs. Most smoothbore models come with interchangeable choke tubes and vent rib barrels, while the slug models come with rifle sights or scope bases, and may have smooth cylinder bore or rifled barrels.

Special purpose models

Special purpose models are intended for self defense, police, or military use. The Model 590 and the eight shot Model 500s are only sold as special purpose models. Special purpose models have short barrels, either 18.5 inches (47 cm) for the six shot models, or 20 inches (51 cm) for the eight and nine shot models but the barrels are fully interchangeable with all models of the 500 family. Most models comes with special designations like SPX™, Tactical, Mariner, and etc.

Special purpose models may be equipped with a variety of specialty parts which may include adjustable stock, "Speedfeed" stock that holds 4 additional rounds of ammunition, pistol grip, ghost ring and fiber optic sights, picatinny rail, forearm band, heatshield, ported barrel, muzzle brake, and even a bayonet lug. All special purpose models comes only in black trim with either blued, non-glare matte blue, or parkerized finishes and comes with drilled and tapped receivers for scope and optics mounting.

It should be noted that "Special Purpose" models are not the same as "Law Enforcement" models; the latter have heavier duty barrels, safeties, trigger guards, and will stand up to harder use.

Law enforcement models

Model 500 Law enforcement combo with red-dot scopeMossberg shotguns currently designated "law enforcement models" are 590A1s. 590A1s differ from other 500/590 shotguns, in that they have heavy barrels, metal trigger guards, and metal safeties. 590A1s are available in 14-inch (36 cm), 18.5-inch (47 cm), and 20-inch (51 cm) barrels. The 590A1 is also used by the U.S. and allied armed forces, having been designed to meet the stricter standards outlined by the U.S. Army.

Model 500s were also previously sold as law enforcement combos in 12 gauge with both 18.5-inch (47 cm) and 26-inch (66 cm) barrels, birch buttstock, pistol grip and sling.

Home security model

The model 500 HS410, or "Home Security" model, is only available in .410, and is specifically designed for defensive use. It comes with a youth-sized stock, a vertical foregrip with, in some versions, a built in laser sight, and a special muzzle brake and spreader choke on an 18.5-inch (47 cm) bead sight barrel. The .410, while by far the least powerful common shotgun chambering, still generates energy in excess of a .357 Magnum, and the spreader choke produces wider patterns, as well as less chance of wall penetration, in the short ranges to be expected in a defensive situation. This model is targeted at the novice user, who needs a simple, easy to use yet effective defensive weapon, and is packaged with an introductory video covering use and safety.

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