Where can you find a replacement spring for a antique winchester model 450 air rifle?

There are shops all around the country that make a living repairing air guns and rifles that are out of warranty. In the past I've searched the web under "air gun repair" and located shops that can make the repairs. There is a shop in Los Angeles "Mac 1 airguns" that has done quite a bit of custom work that is exceptional. They are not fast but very good. See the link below. Also I am providing a web page of several air gun shops that do various work. see link #2 below.