https://www.remarms.com/shotguns/pump-action/model-870/
I just got back from browsing the Remarms website, above, after reading the OP of this thread.
Thirteen of 21 870 models have the "Express" name in them.
I'm guessing somebody made a decision there were too many models/SKUs to the 870 product line and it's likely too difficult/troublesome to have so man SKUs when it's already too difficult to produce just a few models in enough quantity to meet demand.
I'd personally like to see Remarms supply enough parts to outfit all the repair shops and parts sellers/distributors, especially if the parts will fit the prior Remington company's existing 870 models. On a related note, it is & will also be a bit frustrating should somebody would want just a barrel with the various mag tube lengths, plus the finishes, barrel lengths, and barrel types, if buying just a barrel should even ever become an option again as it used to be.
I can only hope the Remington/Remarms 870 survives, as Mossberg also seems to be having trouble supplying the market with 500/590/590A1 models. I would have bought a #50765 Mossberg 590A1 last week but couldn't find one in my local gun stores
. Mossberg, if you're listening, while I have budgeted some money for a new #50765, if I don't find it soon, that money seems to evaporate and get spent on other things.
https://www.mossberg.com/product/590a1-m-lok-50765/
Covid and the supply-chain situation have really hit the consumers & companies in the pump shotgun market (specifically Remington and Mossberg brands) hard.