The Deadly Blunderbuss is a lower level Engineer-made gun.
Deadly Blunderbuss requires an Engineer with a skill level of 105.
The recipe can be learned from the Engineering trainer.
Deadly Blunderbuss as a Quest Objective Edit
This gun is a quest objective for the Horde quest given by Pixel in Splintertree Post in Ashenvale. The Warsong Saw Blades are used in the quest , the reward of which is a Superior (Blue) quality item. An enterprising Engineer might keep the Horde Auction House stocked with these guns since they are needed for this quest.