Just received a Crosman 150 as a gift, it is the single piece barrel breech version. In good shape but could use some blueing, paint, and seals. I was about to order new seals like I do on my other airguns. While apart I was going to rebuild the valve when I seen some people offer a polymer valve they state is better than brass???. I prefer to use the old parts to use as much as I can because this gun is 60+ years old but I am curious, has anyone used the polymer valves? Any luck with them?