Funny that you mention this, as a matter of fact in my game after having taken all the points I wanted in the Int Tree, I went to try out the shotguns extensively. The double barrel is pretty terrible, but the pump is actually very good (and very rare, only found 1 before buying the schematic after 50 hours of playtime). With slugs not needing any brass, that means you basically have infinite ammunition (polymers are a breeze) if you put in the time needed to craft them, and with the right mods, it's surprinsigly accurate.
And yeah... My 2 junk turrets protect the drawbridge entrance of my base, and at that they are perfect for screamers but... I just don't use them in POIs anymore, and I'm clearing them faster by a pretty large margin. Junk drones might really add to the experience, and so will the Tier 3.
By the way, the junk turrets often make the zombies die standing up, which is annoying. I think it mostly happens when they die during the animation of getting stunned and/or getting up from a stun.
@faatal