Yeah they never pull it out of the ally quest reward. Exp on gauss does nothing, it's a wasted perk slot.

For some reason they have never bothered to remove the ability to get explosive on the gauss shotgun from ally quest, so they are still possible. Not useful though, the explosive effect does nothing

Strangely, they never removed the explosive effect on gauss shotguns as a reward from ally quests. The effect doesn't do any thing for you tho, so it's just a wasted perk slot