Two ways you can get this:
Method One - Heroes V VillainsFor this method you'll need to grind out H v V. You need to pick Krennic, as he wields the DT29. Keep in mind though that his alt-fire which is triggered by pressing
does not count towards this, so only use his primary fire. Obviously you'll need to be quick when selecting the villain as other people may want to pick him too. Krennic is on the Imperials, so to make your life easier, head to Multiplayer, List All Modes and pick H v V. If you join and see you are on the rebels side, leave and repeat till you are with the Empire.
Method Two - Hutt ContractRequirements:- 25 kills as Krennic
- Use Personal Shield 10 times
- 50 Blaster Pistol kills
Once again, you could play Heroes v Villains to get the kills as Krennic because hero tokens found in other game modes are often hard to come by. You could get most of the kills for the DT29 done here. Only problem is that the DT29 primary fire is garbage, so you could use the alt fire here for easy kills but it will not count towards the achievement.
The final two requirements are self explanatory.