Looting a piece of Salvage awards you with a perk that stops the turret overheating. This will be very helpful if you are trying to get this in a normal online game as you can just hold the trigger on if you are aiming at people that are slightly hiding. This can of course be done over multiple matches and doesn't need done in one go.
The easiest method for getting this is of course in a private match with other people. Just continuously get them to run in front of you and keep killing them over and over.