The Remington Model 870 is a U.S.-made pump-action shotgun. It is widely used by law enforcement as a defensive weapon and by the public for target shooting, hunting, and self-defense.
The Remington 870 was the fourth major design in a series of Remington pump shotguns. John Pedersen designed the fragile Remington Model 10 (and later the improved Model 29). Working with John Browning, Pedersen also helped design the Model 17 which was adopted by Ithaca as the Ithaca 37 and also served as the basis for the Remington Model 31. The Model 31 was an excellent shotgun, but struggled for sales in the shadow of the Winchester Model 12. Remington sought to correct that by introducing in 1950 a modern, streamlined, rugged, reliable, and relatively inexpensive shotgun, the 870 Wingmaster.
Sales of the 870 have been steady. They reached 2 million guns by 1973 (ten times the number of Model 31 shotguns it replaced). By 1996, spurred by the basic "Express" model, sales topped seven million guns. The 870 holds the record for best-selling pump gun in U.S. history, and the main competitor of the Remington 870 is the Mossberg 500.
The 870 features a bottom-loading, side ejecting receiver, tubular magazine under the barrel, dual action bars, internal hammer, and a bolt which locks into an extension in the barrel. The action, receiver, trigger system, safety catch and slide release catch of the Remington Model 870 shotgun are similar to those used on the Remington Model 7600 series pump-action centerfire rifles and carbines. 20 gauge stocks will also interchange. Several parts of the 870 will interchange with the semi-automatic Remington Model 1100 and 11-87.
There are hundreds of variations of the Remington 870. From the original fifteen models offered, Remington currently produces dozens of models for civilian, law enforcement, and military sales. 870 variants can be grouped into:
- Wingmaster - Polished bluing and glossy wood finishes.
- Express - Inexpensive bead blasted finish and satin wood or synthetic furniture.
- Express Magnum - Inexpensive bead blasted finish and satin wood or synthetic furniture and chambered for 2 3/4" and 3" 12 gauge shells.
- Express Super Magnum - Inexpensive bead blasted finish and satin wood or synthetic furniture and chambered for 3½" 12 gauge shotshells.
- Marine - Synthetic stocks and nickel finishes.
- Police - High luster blued or parkerized finish and satin wood or synthetic stocks.
- Tactical - Numerous versions and options intended for military and police markets.
- XCS - TriNyte coated external metal and nickel plated internals with speedfeed stocks.
- MCS - (Modular Combat Shotgun) - Underslung shotgun used on assault rifles.
- DM - Detachable Magazine - A mag-fed variant that can be fed with 3 or 6-round detachable magazines.
- Harold Murtz. Gun Digest Treasury (DBI Books, 1994), p.193
- Norinco HP9-1, Remington 870 derivative.
- KAC Masterkey
- Remington page for 870
- Remington page for 870 Tactical
- Remington Military MCS page
- Nazarian`s Gun`s Recognition Guide On Remington 870
-  Important differences between Remington 870 Police and 870 Express shotguns