Myowngol

I have done that multiple times, after investing in a set of the proper hones, oil and a low-speed cordless drill. It does help a great deal.

Feb 6, 2014 - 3 1/2 ONLY WITH SUPER MAG RECEIVER'. Right above where shells go in (opposite ejector) it says 'REMINGTON 870'. Serial number is. Feb 16, 2019  Remington 870 Serial Number Lookup| Rem870.com Remington Year of Manufacture Codes maybe found on the barrel of your Remington rifle [or shotgun] on the left side, just forward of the receiver; the first letter of the Code is the month of manufacture, followed by one or two letters which are the year of manufacture.

People tend to shoot crappy ammo in a rough chamber, and never clean it. That frequently leads to extraction woes.
Polishing the chamber helps a great deal, as well as not shooting crappy ammo. I switched over to the Winchester AA loads for classes. It goes on sale for around $80 a case during bird season, and I grab a few cases then.

Remington Serial Number Lookup

I've got two Wingmasters, two Police Magnums, and an Express that has been basically torn apart and rebuilt into a Wingmaster. The Express was free to me.

Remington 870 Receiver Serial Number Lookup

I'd never buy an Express when you can find a used Wingmaster or Police Magnum for under $300 if you look around just a little. I only buy used Remington Police Magnums or Wingmasters these days.

Remington 870 Serial Number Prefix

Hope that helps.