Although widely used, the M16 was not without its problems. Here's What You Need to Remember: As U.S. forces streamed out of bases in the United States bound for Southeast Asia, few would have imagined the M16 rifle, which seemed to have such a rosy future, would encounter such controversy. The weapon which had garnered such glowing reports from American advisers and Vietnamese troops would fall victim to fatal, last-minute decisions and rumor that fueled bad choices at the troop level. The M16 rifle was headed into choppy waters. The M16 rifle is one of the most iconic weapons of the post-World War II era. American fighting men have carried the M16 in one form or another into combat for more than fifty years, from Vietnam to the present day. The story of the original M16, whose descendants the M16A4 and M4 carbine today fight in Syria and Iraq against the Islamic State, goes all the way back to the 1950s and the institutional soul-searching that came after another war—Korea.