Trench Warfare weapon pack available NOW, for FREE! Includes 3 weapons; the Trench Gun Shotgun, the Carl Gustav M/1945 SMG, and the Double 1866 Pistol! : r/ sniperelite
Steam Community :: Screenshot :: Kill a sniper with the Trench Gun to unlock the Trench Gun. Check. Final weapon unlocked.
Sniper Elite 4: How To Unlock The Trench Gun | N4G