I had a Mossberg 835 that did the same thing. It took me a week to figure it out, and I'm willing to bet that you have the same problem. In my gun, the shell latch (the little hook that holds the shells in the magazine tube) was bent too far into the magazine tube. These pieces are spring steel with a factory bend in them. If it is bent inward too much, the action bar will slide behind the latch with the forend racked back. The proper sequence of events is that the action bar on the left side (gun pointed away from you with trigger guard towards the ground) should press in on the shell latch, thus pushing it off of the shell and letting it strip out of the magazine, which can now be loaded into the chamber. I fixed mine by breaking down my gun, as per the Mossberg owners' manual, and put the shell latch in a vise. I then took some of the bend out of it (be careful and don't bend it too much) and reassembled the gun. I got it right the first time, but don't be surprised if it takes a couple times... it's a trial and error process. By the way, to check if your gun has this problem, load the magazine tube to capacity, make sure the gun is on safe, and rack the action vigorously. As soon as a shell does not strip, STOP! do not slide the forend forward. Instead, look into the ejection port, and you will see if the shell latch got activated or not. Hope this helps, and if you have any more questions, feel free to ask. Best of luck!
Pat Brophy
