Several years ago, I took an antique (I mean really antique, like 1870 something) revolver to a local gunsmith. It had a broken mainspring. He said, don't worry, mainsprings are easy. After much delay, and several attempts by him, it still still did not really work. I finally sent it to another person I found online, who specialized in antiques. Unfortunately, that person is out of business now. Bottom line is, mainsprings for antiques are not necessarily easy.