My favorite gun I own is a DeVilbiss GTI Pro. I have several others, but when I shot a lot of HOK clears , if the booth was clean, I can achieve glass without the need to cut and polish! Never painted with anything that lays clear so smooth.
All of my custom bows done by Mike Treadway have automotive clear as a base and grain filler, then sanded and Krystal on top.
They have held up with zero issues. That has been hunting , rain and no great care! I do believe the automotive clear base is what gives them their strength.
They do not scratch easily at all!