Remington 870 action is chalky and not smooth.?

I have two of these shotguns and one of them is from 1996 I believe and the other from 2016. They are both express supermagnums. The one from 2016 seems to always have rust inside whenever I check on it and the action is a lot less smooth. It just feels like a cheap toy when I cycle it and the sound it makes is a lot more dull. When I hold the two guns upside down by the foregrip the action will start to slide on the 1996 version because it's really smooth but the 2016 version is so locked up it won't come close to cycling even when I shake it. I like that the more modern version is painted with real tree camo which helps keep rust off the outside but the internal parts just seem like garbage compared to the older one. Is there anything I can do to make the modern gun cycle smoothly like the older version. Is there any parts I can buy to fix the issue. I already have to buy a new foregrip because it was cheap and is already cracked on the new version.