Originally Posted by ottawadriver

Thanks for the clarification. I was pretty sure anything in 5.56 could fire .223 but S&W lists both calibers on most of the M&P rifles except the Sport. Maybe they did this as a ploy to get people to step up to the full models. Just need to sell some of my R/C planes to make the wife happy and provide play money for the M&P Sport and my M&P 9.