Bo-Mar Cut Milling timelapse.

Published on February 9, 2022
Duration: 2:24

This video demonstrates the advanced gunsmithing process of milling a Bo-Mar cut into a 1911 slide to accommodate an adjustable rear sight. The expert instructor guides viewers through the precise CNC machining steps, including initial channel milling, deepening the profile, drilling mounting holes, refining the sight base, and finally tapping the threads for screw installation. The demonstration highlights the use of various cutting tools and the importance of coolant for a clean, accurate modification.

Quick Summary

Milling a Bo-Mar cut into a firearm slide is an advanced gunsmithing process using CNC machinery. It involves creating a precise channel for adjustable rear sights by milling, drilling mounting holes, and tapping threads. Proper use of tools like endmills, drill bits, and hand taps, along with coolant, ensures an accurate and durable modification.

Chapters

  1. 00:07Initial Bo-Mar Cut Milling
  2. 00:20Deepening Sight Channel
  3. 00:34Drilling Mounting Holes
  4. 00:57Refining Sight Channel Base
  5. 01:10Tool Changes and Finishing
  6. 01:48Tapping Screw Threads
  7. 02:03Bo-Mar Sight Installation

Frequently Asked Questions

What is a Bo-Mar cut and why is it used on firearm slides?

A Bo-Mar cut is a specific dovetail profile milled into a firearm slide, primarily for the installation of adjustable rear sights. These sights allow for precise windage and elevation adjustments, making them popular for competition shooting and custom builds where accuracy is paramount.

What are the key steps involved in milling a Bo-Mar cut?

The process involves using a CNC machine to mill the initial channel, deepen and refine the profile, drill mounting holes for the sight screws, and then tap those holes for threading. Finally, the adjustable rear sight is installed.

What tools are essential for milling a Bo-Mar cut?

Essential tools include a CNC milling machine, various sizes of endmills and drill bits, a hand tap for threading, a vise for securing the workpiece, and cutting fluid or coolant to aid the machining process.

Why is coolant important when milling firearm slides?

Coolant is crucial during milling to reduce friction and heat buildup, which can damage the cutting tool and the workpiece. It also helps to lubricate the cut, allowing for a smoother operation and a cleaner finish on the milled surface.

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