Simplifying polycounts modifier

[Lonecat Nekophrodite]

1. For in game units. what is the most optimum unit polycounts that will not affect the game?
2. What are recommended blender simplification tools that will not ruin overall model pieces look.
This is what I have now (downloaded actually). from this person.

Colt Single Action Army Revolver - Download Free 3D model by pablord3dart

My first project for Sketchfab. A simple and quick made revolver based on the popular Colt Single Action Army. Made on Blender and texturized on Substance Painter. - Colt Single Action Army Revolver - Download Free 3D model by pablord3dart

sketchfab.com

What I want is Fieldcannon crew pistol (for late industrial era fieldcannon crew). what are poly reductions without having to make a new textures entirely (i.e. perserving UV Map layouts with acceptable reduced tris)?

Original files including the very project that has original fieldcannon crew pistols https://drive.google.com/file/d/1B-8JgSaaipHJTh6Ro46Rp0is8R8rqWwu/view?usp=sharing
Original files being poly intensive !!!

WIP (beginning actually)

 

[ghost toast]

depends on the in game view,

mostly in my experience it really depends on the pixels color, and the contrast between them
to much of a difference results in flickering graphics

I don't know anything about reduction tools but I can make you a new lower polycount gun. But the gun even with that high of a Polly count will probably still work.