Auto Reframe for Video Gameplay

I want to use the Auto Reframe effect for gameplay after I livestream. However, I am not quite sure how to make it track the motion of my weapon instead of the webcam frame.

The 1920 x 1080 frame looks like this.

After using the Auto Reframe effect and changing the video sequence settings to 1080 x 1920 (16:9 Ratio), this is what it tracks vs. what I want it to track.