The Korean Joint Chiefs of Staff have announced the cancellation of the S&T Dynamics XK13 that has been in development for a number of years. The OCSW-style (Objective Crew Served Weapon) automatic weapon fires 25mm grenades. The military had expected it to be able to replace both their K4 automatic grenade launchers and M2 Browning .50 cal. machine guns. Three rounds were in development for it, a High Explosive Air Burst round, an Armor Piercing round and a Target/Practice round.

S&T Dynamics XK13

The weapon was apparently 22 lbs overweight and did not have sufficient anti-air capabilities (a large caliber grenade launcher with a parabolic trajectory and low ammunition count being used against aircraft?). The Korean military will instead be working with S&T on a new 40mm automatic grenade launcher to replace heavy machine guns. It will be ready sometime between 2016 and 2021.

Thanks to @uribury871 for the tip.