I haved used the spray on bake on finishes from brownells with good results. I used the teflon in diff. colors to camo one gun. It is just like using spray paint, spray one coat let dry spray second coat let dry and then bake it. Can even be used on inside of action with no problems. I have used it shotguns and rifles. Make sure to plug the bore when you spray it. I just pushed a patch into the barrel so it stuck out the crown.
