10.5 inch barrel; Seekins Precision BAR; Ferfrans Modular Muzzle Device...and a badass T-shirt from Article 15 Clothing:
Pew Professional by Triple Bravo, on Flickr
10-8 Performance will soon be releasing a new mag well and extended magazine base pads for the Smith & Wesson M&P pistol.
More intel here: http://modernserviceweapons.com/?p=5340#comment-13763