Mossberg sells the front Picatinny rail screws for the 930 SPX for $2 a piece + shipping. Call their customer support and ask for part number 18444MT. Screw them in with a bit of Loctite blue (threadlocker) to make sure they don't fall back out.
I had the problem of shells hanging up in the magazine tube of my 930 SPX. I was able to fix the problem following some of the suggestions in this thread. I just wanted to put what worked for me out here.
The reason for the hang ups has already been mentioned earlier in the thread. The factory...