Making the Scope Base Mounting Screws Nearly Perfect | MidwayUSA Gunsmithing

Published on August 2, 2013
Duration: 3:06

This guide details the process of upgrading scope base mounting screws from standard 6-48 to stronger 8-40 size, a critical modification for rifles experiencing heavy recoil. Larry Potterfield, demonstrating master gunsmithing techniques, explains the necessity of this upgrade to prevent screw shearing and ensure scope reliability. The procedure involves precise drilling and tapping of both the rifle receiver and the scope bases, utilizing specialized tools for accuracy.

Quick Summary

Upgrade your rifle's scope base mounting screws from 6-48 to 8-40 for enhanced strength and reliability, especially on heavy recoil platforms. This process involves precise drilling and tapping of both the receiver and scope bases using specialized tools like carbide drill bits, plug gauges, and taps. Proper technique prevents screw shearing and maintains scope zero.

Chapters

  1. 00:00Problem with Standard Scope Screws
  2. 00:30Tools and Setup for Upgrade
  3. 01:12Drilling and Tapping the Receiver
  4. 02:03Modifying Scope Bases

Frequently Asked Questions

Why should I upgrade my scope base mounting screws?

Upgrading from standard 6-48 screws to 8-40 screws significantly increases the strength and reliability of your scope mounting system. This is crucial for rifles with heavy recoil, as it prevents the screws from shearing and ensures your scope stays zeroed.

What tools are needed to upgrade scope base mounting screws to 8-40?

Essential tools include a #28 carbide drill bit for the receiver, an 8-40 tap, a #19 drill bit for the bases, appropriate plug gauges (.114" for receiver, .143" for bases), a V-block, a precision level, and cutting fluid like Tap Magic.

How do I properly tap new threads for 8-40 scope base screws?

When tapping, use cutting fluid and back the tap off every half-turn. This technique breaks the chips as they form, preventing them from binding the tap and ensuring clean, strong threads in the receiver or scope base.

Can I use standard tools for this scope base screw upgrade?

While some basic tools are used, precision is key. Specialized tools like carbide drill bits, specific plug gauges for centering, a V-block for stability, and a tapping guide are recommended for a successful and safe upgrade to 8-40 screws.

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