The XCS is an 870 Marine that is PC coated black with the same coating as the Tactical Models with that mess on it.
There is only one 870 and they only differ by finish, furniture and some small parts, however the Marine does have electro plated internal parts but these are the exact same parts as in every 870 so there is not difference in quality.
You use the word magnum like these are different. Every Express, every single freaking one ever made is a magnum and built on a 3" receiver except some are called Super Magnums because the can eject 3.5" shells and are built on the same reciver but with a longer ejection port. So there is no such thing as a non magnum Express.
The early P models were simply Wingmasters with short barrels and plain wood stocks so yes, some of these were 2 3/4" receiver but we shot 2 3/4" magnum 00 buck from them so I guess they were magnums also. Now all 870's are either 3" or 3.5" receivers and have been for years but you may still be able get a high dollar 2 3/4" Wingmaster Trap model. But this is just a blued 870 with high dollar stocks and all the parts in it are the same parts as in the Express except for the Extractor.
There has never been a stainless steel 870 and the only stainless steel part on a Remington shotgun is the magazine tube on the semi-autos. The Marine is not stainless steel.
I think that about covers it.
J.D. McGuire, Owner
AI&P Tactical, LLC
Remington Factory Certified
Law Enforcement Armorer