Beginning in 1950 the Remington Model 870 Wingmaster left all other pump guns in the dust.
Wife Nancy and I were in Ilion a few years ago getting Le Grand Tour from the PR guy when he took us into a large room with a glassed in module in the center, sort of like a big truck cab. Inside was a vertical square column with four blocks of steel locked in place on each side. A mechanical arm, directed by a computer, selected a cutting tool and progressively made cuts on the four blocks of steel on a side; the machine paused and the column turned 90 degrees and more cuts were made, then 90 degrees twice more, cutting tool replaced in its place, new tool selected...etc...as the actions of 870s were starting to materialize without the help of a human hand.
I commented to the Remington guy that I had just bought an 870 Sabot deer gun for $219.95 at a big box sporting goods store and asked how they could justify the plant, equipment, raw materials, computer and labor to make something so complex that retailed for so little. He said that it was even worse than I envisioned; Remington only geared up to make 870s when a large order came in, say 10,000, and the 800-pound-gorilla retailers were in the driver's seat as to wholesale pricing--Remington had to take it or leave it, accept a low ball price and a long delay billing or the order would go somewhere else. After all, the 870 is long out of patent. No wonder Remington is reduced to being a financial ploy of a well-heeled group of nameless investors. The American gun making business at the "everyman" price level is tough and getting almost impossible. EDM