Winter Soldier Grenades were special grenades used by Winter Soldier on his missions. They were saved by Bucky Barnes after he started recovering his memories.
While hunting Captain America, Falcon and Black Widow, Winter Soldier pursued Romanoff through the streets of Washington, D.C., as the civilians ran for cover. Barnes soon believed he had Romanoff cornered when he heard her voice from behind a parked car. In an attempt to kill his target, Winter Soldier dropped a grenade but soon discovered it was a trick and was ambushed as Black Widow jumped onto his shoulder and attempted to strangle him.
Barnes continued to ride away from Black Panther while the still determined Joint Counter Terrorist Centre agents followed behind in their cars. Coming to the end of the tunnel, Barnes used one of his grenades to destroy the roof, hoping to trap his attackers and get away. However, Black Panther was able to gain extra speed by jumping on Falcon's back, and knocked Barnes off his bike before Captain America kept him from killing his friend.