My receiver has developed a crack down beside the magazine tube. It doesn't seem to be in a load bearing spot, or that there is any large pressure there. I would love to make a 12.5" barrel NFA registered SBS out of it because I love the action so much, but I have a few questions. Pics here: 1. I have shot this quite a bit since the crack was there (I thought it was a scratch), and it seems to be fine. Should I absolutely replace the receiver? 2. If the answer to number one is yes, where would I get one? 3. How in the hell do I get it to an FFL dealer from a website if Gunbroker or something is the answer to number 2. All help is appreciated guys! Thanks in advance.