If the FAQ info doesn't help, H&R may have to take a look at it. Are you shooting handloads or factory? With a live round in the chamber, place a straightedge across the round and chamber face, the headstamp of the round should be flush with the chamber face, it may even be slightly below it, but it shouldn't be above the chamber face at all unless the barrel to frame gap is excessive. If it's above the chamber face, it can keep the latch from engaging sufficiently and pop opens can happen. Even if you slam it shut, it won't close enough, this happens with handloads where the shoulder of the case isn't pushed back enough when resizing.
Tim