ECM R11 & Norsso 3.7” XL

Published on July 22, 2025
Duration: 2:53

This video provides a detailed, step-by-step guide to assembling a custom SIG Sauer P365 pistol. It covers the installation of the Fire Control Unit (FCU) into an XMACRO grip module, the assembly of a Norsso R11 slide with a Norsso barrel, and the mounting of a Holosun 407K X2 optic and Surefire XC3-A weapon light. The guide emphasizes proper torque specifications and visual checks for accessory security, demonstrating an intermediate level of firearm assembly skill.

Quick Summary

This guide details assembling a custom SIG Sauer P365, integrating a Norsso R11 slide, Norsso 3.7" barrel, Holosun 407K X2 optic, and Surefire XC3-A light. Key steps include FCU installation, slide assembly, optic mounting with threadlocker and torque wrench, and visual checks with witness marks.

Chapters

  1. 00:00Introduction & Component Layup
  2. 00:13FCU Installation in Grip
  3. 00:35Barrel & Slide Assembly
  4. 00:58Pistol Assembly & Function Check
  5. 01:15Optic Installation
  6. 01:35Witness Marking Optic Screws
  7. 01:58Weapon Light Installation
  8. 02:25Final Product Overview
  9. 02:34Loaded Magazine Function Check

Frequently Asked Questions

What are the key components for building a custom SIG Sauer P365 as shown in the video?

The build features a SIG Sauer P365 Custom Works FCU, an XMACRO grip module, a Norsso R11 P365XL slide, a Holosun 407K X2 optic, a Norsso 3.7" 9mm barrel, and a Surefire XC3-A weapon light.

How is the Holosun 407K X2 optic installed on the Norsso slide?

The optic's mounting screws are treated with threadlocker. The Holosun 407K X2 is then positioned and secured to the slide, with screws torqued to specification using a Wheeler Engineering FAT Wrench.

What is the purpose of witness marks on optic screws?

Witness marks, applied with a permanent marker, serve as a quick visual check to ensure that the optic mounting screws have not loosened after installation and firing.

What tools are essential for this custom P365 build assembly?

Essential tools include a non-marring hammer for FCU installation, threadlocker for optics, a Wheeler Engineering FAT Wrench for precise torque application, and a permanent marker for witness marks.

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