Guys need help ordering correct butler creek caps for two scopes that I have. One is vortex viper pst 4-16 and the other is vortex viper pst 1-4 power. If some one can help me get the part number or the size, that would be great. I can't figure out if I need to get them right on the spot as far as size of the scope or size smaller so they fit nice and snug. So if some one has those optics please be a friend and help me out. I would really appriciate that.