I had the same recently, and it left me horse-laughing. Running a raid on Interchange and brought a Saiga-12 FA that I'd picked up from Tagilla. I complete forgot that the FA meant full-auto. The first target I came across couldn't have been more than 10 feet from me, and he paused like a deer in the headlights (taclights?). I fired and 20 rounds of flechette dumped instantly. It shot a perfect circle pattern around him on the wall behind him and then he ran away. It was like a scene out of a cartoon. I had to pause playing for a second I was laughing so hard. Then I realized my raid was FUBAR with that shotty. I went through more than 100 rounds before I got my first kill, and promptly stripped them to rearm with something to get me out of the raid.
I remember the Make Shotguns Great Again mod fixed a lot with shottys but doesn't look like it's up to date. I went back to using my kitted out MP-155 as it still gets the job done.