Burt Gummer owned and used an 870.
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. The basic trigger group design was first used in the automatic 11–48. 12 gauge stocks will also interchange on the older 12 gauge sized 20 gauge receivers, although modification is needed to fit the smaller sized 20 gauge receivers employed since the late 1970s. Several parts of the 870 will interchange with the semi-automatic Remington 1100 and 11–87.
The original 870 models were offered with fixed chokes. In 1986 Remington introduced the new Remington "Rem Choke" system of screw-in chokes (also fitted to Remington model 1100 auto-loading shotguns at the same time). Initially, the Rem Chokes were offered only in 12 gauge in barrel lengths of 21", 26" and 28". The following year the availability was expanded to the 20 gauge and included other barrel lengths.
Production 870s for over 30 years had a design whereby a user could fail to press a shell all the way into the magazine when loading such that the shell latch did not engage the shell, and such actions could tie up the gun. This was caused by the shell which slipped out of the magazine under the bolt in the receiver to bind the action, requiring rough treatment of the action or even disassembly to clear by the uninitiated. The potential issue was resolved with the introduction of the "Flexi Tab" carrier. Guns with this modification can be identified by the "U"-shaped cut-out on the carrier, visible from below the gun. The cut-out, combined with a modified machining on the underside of the slide assembly, allows the action to be opened with a shell on the carrier.