SeaScout
OK then, progress!
I thought that was the case, failure to feed in the chamber. This problem can be caused by a number of issues and therefore may have one or more answers. The problems can include, rough receiver or chamber marks, the elevator angle being to low or high and even ammo related. Start by taking your weapon apart so that you can really inspect the chamber and receiver well. You may find rough surfaces that can be polished out. There are several very good threads on how to do this. Take the time to read them closely. It will really help. Not hard either, just follow the advice as it is laid out. Take the time to clean the piss out of everything while you have it apart. Check the receiver and polish as needed. Take it to the range after this with at least three quality different brands of ammo, no cheap crap. All heavy loads. Run the snot out of it hard. Do not mix brands of ammo and keep accurate note as to what is going on, when is it going on. You can handle this better than just sending it back to Mossberg at this point. And if you do have to send it back, you will be in a better position to help them by better understanding your situation. Let us know how it goes.
Best...