Years ago I had my LGS replace a sight blade and we had a discussion about the breaking sight screw. As I remember, there was a possibility that the screw might break and need to be replaced. I have replaced a few rear sight blades, but do not recall breaking a screw. These were all older Smiths. It is quite possible that the breaking screw possibility has been eliminated on the Classic models. Suggest you call Brownells Customer Service. They will have the answer and any parts you may need.