TCW: That is rather uncommon for a Mossberg 500. I got rid of my 870 because of jamming problems, probably my fault, but a shell would back out of the magazine tube before cycling and tie up the gun. On the Mossberg if this happens, the shotshell just falls on the ground. The action design is what I like about the 500. Dead reliable. I have a ghost ring sight 590, too, and have never had any problems with its functioning. If your shotgun is tapped with screwholes on top like my Turkey gun, make sure the screws haven't worked their way too deep into the receiver.