Browning Hi-Power Full Custom in .40 S&W with .357 Sig Conversion

Published on November 28, 2022
Duration: 4:58

This guide details the modifications and components of a custom Browning Hi-Power Mark 3, originally chambered in .40 S&W and converted to .357 Sig. It covers slide and frame enhancements, specific sights (Trijicon HD, Heinie Mil-Spec Ledge), a KKM Precision barrel, trigger profiling, beavertail installation, safety modifications, and Cerakote finish. The guide also emphasizes the critical differences in magazine feed lips for reliable .357 Sig feeding and the structural advantages of three-lug .40 S&W/ .357 Sig barrels over two-lug 9mm barrels.

Quick Summary

This custom Browning Hi-Power Mark 3, originally in .40 S&W, has been converted to .357 Sig. Key modifications include a beefed-up slide, a KKM Precision barrel, Trijicon HD sights, Heinie rear sights, a modified trigger, beavertail, and Cerakote finish. Crucially, .40 S&W magazines are required for reliable .357 Sig feeding due to their wider feed lips.

Chapters

  1. 00:00Introduction & Caliber Conversion
  2. 00:20Slide & Frame Modifications
  3. 00:37Barrel & Front Sight
  4. 00:50Rear Sight & Hammer
  5. 01:07KKM Barrel & Caliber Explanation
  6. 01:46Trigger & Ergonomic Modifications
  7. 02:18Trigger Guard & Serial Number
  8. 02:36Safety & Finish
  9. 02:57Trigger Performance Demo
  10. 03:11Magazine Differences
  11. 03:58Barrel Lug Comparison
  12. 04:27Conclusion & KKM Barrel Fit

Frequently Asked Questions

What are the key modifications on this custom Browning Hi-Power Mark 3?

This custom Browning Hi-Power Mark 3 features a beefed-up slide, a KKM Precision .357 Sig conversion barrel, Trijicon HD front sights, Heinie Mil-Spec Ledge rear sights, a modified G.I. Garthwaite profile trigger, a beavertail grip safety, and a Graphite Black Cerakote finish.

Why are .40 S&W magazines important for a .357 Sig conversion?

For a .357 Sig conversion on a .40 S&W platform, .40 S&W magazines are crucial because their feed lips are slightly wider, allowing for reliable feeding of the .357 Sig cartridge. 9mm magazines are too narrow and will not feed .357 Sig rounds properly.

What is the advantage of a three-lug barrel in a .40 S&W or .357 Sig firearm?

A three-lug barrel, as seen on the .40 S&W and .357 Sig barrels, offers increased strength compared to the two-lug design of 9mm barrels. This extra lug is vital for handling the higher pressures generated by these more powerful cartridges.

How does the trigger on this custom Hi-Power differ from a factory model?

The factory trigger has been flattened to a G.I. Garthwaite profile, enhancing ergonomics. It functions as a single-stage trigger with no discernible take-up before a clean break and a distinct, audible reset.

Related News

All News →

More Gunsmithing & DIY Videos You Might Like

More from MK3 Firearms

View all →