I've tried a few mapsets with this and the biggest problem I have had is that the base shotgun is borderline useless against most enemies given the amount of punishment they can dish out and how quickly. It's better off for me to try to stunlock an enemy with an automatic and use more ammo than just hope I can take out a target with 1 shot with the shotgun which so far only seems to work on the fleshiest of soldier enemies. The shotgun went from being frontline to being a fallback weapon.