Try a new magazine or adjust the one you have. It isn't letting the rim come up enough to be caught by the bolt so either the mag is sitting too low or the lips are wrong. Try pushing up on the mag while working the bolt. If that solves the problem adjust the mad retainer to make the mag sit higher. If pushing up doesn't then you need to open up the ears at the back a bit. If it is a tube feed then you need to take it apart and clean it as the shell is hanging up in the tube. Check for dents and a weak spring while it is apart.
One other thought, the tube feed ones have what is called a cartridge stop and a cartridge interrupter mounted into the receiver. Check that they are working properly, jack the action open, if the shell does not move onto the carrier, push down on the interrupter tab to see if the shell now releases into the carrier. There are some very good schematics on line, the Mossberg Store has some great ones, if you don't recognise what I am talking about.
Mossberg makes both a tube fed tactical and a mag fed tactical and I could not tell from your description if it was the 500 or 590M. That is why I tried to give you fixes for both. Since yours is the tube, my bet is the cartridge interrupter is the issue.
So i watched the action the feed closely and you are correct. As the elevator shifts it does not engage with the stop which remains in place holding back the shell.
I have removed both the stop and interrupter but have no idea whether there are any irregularities. The interrupter looks perfectly flat to my eyes, however the stop has a slight curve such that if were to bend it straight it would impede the shell less. However, if i do that it seems to me the elevator would be even less likely to push the stop aside. I am wondering whether it might be the elevator?
Take it to FPS and get him the fix it for you. You can do more damage than good if u don't understand exactly what u are doing and parts aren't always easy to get if u break something.
mossberg feeding problem
Linear Mode
