I have a 16 gauge CSMC Model 21. I don't know what you're planning on using this gun for, but remember, they are heavy. Mine weighs 7lbs, 6oz. That's a lot of weight to be lugging around in the field.
If requested, I'm sure some fat can be removed. I'd be more concerned about this than case coloring. But, if you want it, you should have it. A custom gun should be done your way. Don't worry about what others have and get what suits you.