BudsGunShop.com - Are any smith and Wesson pistols single action?

Yes the S&W 1911 series are single action The M&P guns are striker fired

Rob, there is much debate on this Sir. In the M&P designs, the cycling of the slide fully loads the striker. The trigger is not used or designed to add any additional significant striker spring compression. It performs no function of any double action mechanism. The trigger does not "pre-load" the striker. All M&P pistols are classified as DAO, although I can see why some folks believe otherwise, since the pre-set striker is only pushed back a short distance during the trigger press and there's no second strike provision.