SMITH & WESSON M&P 15 AR15 FOR SALE. THIS RIFLE COMES WITH A CALLAPSIBLE STOCK THAT MEASURES 35.5" WHEN COMPLETELY EXTENDED AND 32 ¼" WHEN COLLAPSED. THIS FIREARM HAS A BARREL LENGTH OF 16.5" INCLUDING THE MUZZLEBREAK AND 15.5" WITHOUT. IT IS CHAMBERED IN 5.56 AND HAS A 1/9 TWIST.