I have a 12 ga. 870 super magnum. At first when I shot low brass shells (cheapest Federal), they were getting stuck in the chamber, and sometimes I had to bash it on a bench or rack it really hard to get them out, which meant that chamber needed a hone or polish, but which also meant that extractor was rock solid, because the way I bashed it on the bench, I dunno how it did not fail. I then tried to polish the chamber with steel wool, but it did not work, it was still to tight. I sent the barrel only to Remington and they returned it the same week, with chamber honed and polished, all free of charge, since it was still under warranty. Since then the gun has been VERY reliable, not a single jam, not a single problem.
At first I was noticing some rust (likely because I was shooting in snow) but after I covered it with a few layers of CLP, it is all good, it was sitting out in snow last time I shot it and no rust.
The only thing I would improve in the gun is the dimples in the magazine that prevented me from installing a mag extension, but after I flattened them out using a hammer and a ratchet wrench socket, it is all good.
All in all, the gun is a very tough, no bull**** workhorse. I highly recommend.