The problem with the older weaver mount that only secured via the tenon and sight screw is the small sight strap screw will often be sheared off by recoil, as low as 38 Special. That's the primary reason why they are no longer made. Having to drill out and re-tap that little hole is a pain if you know how and impossible if you aren't a machinist. If you take your 53 and have it drilled and tapped (under the rear sight strap, and not drilled completely through the top strap), you can replace the rear sight and not see the evidence of having been drilled and tapped.