Gunnar Jansen (Dolph Lundgren) uses a M79 grenade launcher, loaded with 40 mm Buckshot and a laser sight during the oil tanker sequence, which blows away the entire torso of one luckless pirate. It is also used later in the film by an enemy guard he uses it to destroy a truck Ross is standing next to. Information and images from IMFDB.org.
Gunnar shooting the pirate.