Making the Scope Base Mounting Screws Nearly Perfect | MidwayUSA Gunsmithing

Published on August 2, 2013
Duration: 3:06

This video details upgrading standard 6-48 scope base mounting screws to stronger 8-40 screws, essential for handling heavy recoil from magnum cartridges on rifles like the Remington Model 700. It covers the precise drilling and tapping process for both the receiver and scope bases, emphasizing the use of specific drill bits, taps, and plug gauges for accuracy. The tutorial highlights the importance of proper setup, including securing the receiver in a V-block and using a mill vise for the bases, to ensure reliable scope mounting.

Quick Summary

Upgrade 6-48 scope base mounting screws to 8-40 for enhanced reliability, especially on high-recoil rifles. This involves precise drilling with a #28 bit and tapping with an 8-40 tap on the receiver, and enlarging holes in the scope bases using a #19 bit.

Chapters

  1. 00:00Problem: Weak Scope Screws
  2. 00:30Tools & Setup for 8-40 Upgrade
  3. 01:12Drilling & Tapping Receiver for 8-40
  4. 02:03Modifying Scope Bases for 8-40 Screws

Frequently Asked Questions

Why should I upgrade from 6-48 to 8-40 scope mounting screws?

Standard 6-48 screws can shear under the heavy recoil of magnum cartridges common in safari rifles. Upgrading to 8-40 screws provides significantly increased strength and reliability, preventing scope mount failure.

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

You'll need a #28 carbide drill bit for the receiver, an 8-40 tap, cutting fluid, a V-block for securing the action, parallels, a precision level, and a mill vise for modifying the scope bases.

How do I properly drill and tap the rifle receiver for 8-40 screws?

Secure and level the receiver, center the drill bit using a plug gauge, drill with a #28 bit and cutting oil, then tap with an 8-40 tap, backing off every half-turn to break chips.

Do I need to modify the scope bases as well when upgrading to 8-40 screws?

Yes, the scope bases must also be enlarged. They need to be centered in a mill vise, drilled with a #19 bit, and potentially counterbored to accommodate the larger 8-40 screw heads.

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