See
Extractor to Ejector conversion, it's a couple topics below the 2nd generation underlug pic.
If the extractor claw works in and out of the underlug when you open and close the barrel, it must be missing the rim.
A properly functioning extractor has a lot of force on the spent case, I loaded some 440gr CP bullets for the 500S&W, apparently got some bullet lube on the outside of a case, it stuck in the chamber, with normal opening force the action wouldn't open, so I broke it over my knee and it forced the case out to the end of the travel, then I had to use pliers to get it completely out of the chamber. So I know it has plenty of force to extract a stuck case if it's working right, it's either gonna rip the rim off, or it ain't gonna open. Could be a broken roll pin on the cam. Just about any way ya look at it, unless you want to fix it yourself, sounds like it'll need to go back to H&R for repair.
Tim