The RPD is a belt-fed, open bolt machine gun in 7.62x39. It was designed in Russia as a squad level belt fed that was lightweight and cheap to produce. The russians eventually replaced it with the RPK which is a larger bipod fired AK variant because it uses the same magazines as the AK. Many communist bloc countries continued to manufature and use it for decades. It was used extensively in vietnam by our comminust enemys.