I did a few tweaks on the trigger group to fix the mesh, and make things a bit cleaner for printing.

When i first opened the file in SuperSlicer i noticed when it sliced there was several parts of the model that were broken. I took the model into Blender and fixed all the overlapping faces, and fixed the model to be manifold.

I then made the top surface of the circle for the selector knob percetly flat so it would print in one clean layer. 

I also added a small gap underneath the selector cirlce so you wont have to sand the recess anymore. I left a little part to act as a support you can pop off after it prints.

I also reduced the clearance on the gap for the trigger spring. its a little smaller and will make a nicer print while still remaining functional.