If some gangs' animation with Shotgun looks pretty weird like Citizen and Combine's shotgun animation are mixed, You've probably downloaded this.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1908910131
I can't do anything because it's addon of shotgun animation to Metro Cop, I recommend you to remove it if you don't like some Gang's combine Shotgun animation.
CGF, CAF and OCBG included.