The gloss paints will hold up better, and be tougher than the flat. The flat will have the least amount of reflection. It all depends on what you're going to do with your rifle. I just painted my pred rifle white since there's snow on the ground. When the snows gone, I'll paint it camo. Since I'm going to be changing the color in a few months, I'm not going to clear coat it. If I were going to leave it one color, for the most rugged paint job, I would use a primer, then a quick pass over with some steel wool, then gloss for the camo, since it will be the toughest, and then a matte urethane for the last coat or two. Rustoleum has a matte clear coat, I have a can but I haven't used it on a rifle yet. I usually just stick with straight flat camo, then if it gets scratched or if I need to change colors overnight, i just go right over it.