Lastly, I have zero faith in this gun. To be honest I don't even want it back, the only reason I would send it in is to have it fixed for when I trade it. I had a failure to feed or failure to go back into battery at least once a magazine. Would I be out of line asking the retail store for store credit back on the purchase? Would S&W be willing to do anything? I'd almost rather have anything else back.
Like any other item made by man, guns can fail out of the box. I've had similar issues with another brand, but in less than a week I got a replacement part and it has been 100% since. If I were you, I would get in contact with S&W. I'm sure they will fix it for you. Probably just something small, and you will be back to shooting in no time.
You could try and ask for credit, but I doubt that will go very far... I guess that really depends on how much business you give them though. Again, I would send it off and see how it shoots when you get it back. You may be pleasantly surprised.