Is the original follower catching the spring completely on the underside? There's nothing that can just up and break besides the spring, follower and their relationship. Look for a clean mag box, and fully seated spring. Beyond that.....is the spring going flat?

Originally Posted by BrentD

I would not buy something that runs on any kind of primer given the possibility of primer shortages and even regulations. In fact, why not buy a flintlock? Really. Rocks aren't going away anytime soon.