The advice is all good. It's a complex system, especially being the first of its kind. Later gas-operated autoloaders had fewer parts, and were easier to build and maintain.
Just as a point of historical interest, here's my early-WW2-vintage Model 11 riot gun. Remington used up all the checkered stocks and roll-engraved receivers before going with plain ones later in production.
This one is "The Sportsman", which had a two-shot magazine tube for waterfowl hunting, rather than the four-shot magazine. It was not usually made as a riot gun, but the government was desperate for shotguns, so Remington made both three and five-shot versions to use up the parts on hand before going over to the "mil-spec" version.
Since it used commercial parts, it had the commercial blue finish, still visible on the underside of the barrel, where the forearm shielded the finish from the elements.
Remington was so concerned that the troops, as possible future Remington customers, would look down on the parkerized finish of the later riot guns that they marked the left side of the receiver with "Remington Military Finish" so you couldn't mistake them from their fine commercial bluing. The military markings consisted of a "US" on the receiver, and a ordnance "flaming bomb" on the receiver and top of the barrel. As with all trench guns and riot guns, the barrel was only 20 inches, and cylinder bored.
