I bought a M&P 15 in the first week of April(don't remember exact date), shot it once, functioned fine, great gun. Last night I took the forearm off to discover:
http://i41.photobucket.com/albums/e294/andyjs3589/STA73306.jpg
http://i41.photobucket.com/albums/e294/andyjs3589/STA73307.jpg
http://i41.photobucket.com/albums/e294/andyjs3589/STA73308.jpg
The metal lining is bent and the forearm was cracked. I know 100% that I did not do this and that it came like this. I do have to credit S&W though on their customer service, I was on the phone for about two minutes today and they are shipping me out a new forearm asap.