I just tried to stick a mag in one of my AR's like that.....Didn't work so well !! She must have really slammed that thing in there to get it to stay lol.
My thought is that this was a staged shot done after the fact. She may be a staff type that the newspaper asked to pose for the photo and one of the other 'real' officers was asked to set the weapon up for her. I'm thinking that who ever put the mag in the rifle for her, put the mag in backwards to make her look like the posier she may have been. Either that or she was a very fresh rookie that another officer suggested pose for the shot and was the target of a practical joke.