How To Zero The AR15A4 / M16A2 / M16A4: Dial In The Rear Drum For Distance

Published on August 11, 2020
Duration: 11:11

This guide details the process of zeroing and utilizing the A2/A4 style rear sight drum on AR-15 and M16 platforms, as demonstrated by Mrgunsngear. It covers understanding the dual apertures, calibrating the elevation drum with an Allen key, and applying sight settings for various distances, including an Improved Battle Sight Zero (IBSZ) method. The instruction emphasizes practical application for accurate shooting from close range to extended distances.

Quick Summary

Zeroing the A2/A4 rear sight drum on AR-15/M16 rifles involves an initial 25-yard zero using the front sight post. Subsequently, a 1/16 inch Allen key calibrates the elevation drum by aligning its markings with the sight base. The dual apertures cater to different ranges, while the drum's meter settings facilitate accurate long-range shooting by compensating for bullet drop.

Chapters

  1. 00:00Introduction to A2/A4 Sight Zeroing
  2. 00:45Overview of Sight Controls
  3. 01:13Understanding Dual Apertures
  4. 02:00Calibrating the Elevation Drum
  5. 04:18Improved Battle Sight Zero (IBSZ)
  6. 05:22Live Fire Zeroing Demonstration
  7. 07:20Long Range Testing

Frequently Asked Questions

How do you zero the A2/A4 rear sight drum on an AR-15 or M16?

Begin by ensuring the rifle is unloaded. Use the front sight post for initial elevation and windage adjustments at 25 yards to achieve Point of Aim/Point of Impact. Then, calibrate the rear sight drum using a 1/16 inch Allen key to match the sight base's tick mark.

What is the purpose of the dual apertures on the A2/A4 rear sight?

The A2/A4 rear sight features two apertures: a larger '0-2' aperture for close-range targets (0-200 yards) and a smaller precision aperture for longer distances. The larger aperture is positioned 2.5 MOA lower than the precision one.

How does the elevation drum on the A2/A4 sight work for long-range shooting?

The elevation drum is marked with meter settings (e.g., '4' for 400 meters). By dialing the drum to the appropriate setting after zeroing, you can achieve Point of Aim/Point of Impact at that distance, effectively compensating for bullet drop.

What tool is needed to adjust the A2/A4 rear sight drum?

A 1/16 inch Allen key is required to adjust and calibrate the elevation drum on the A2/A4 style rear sight system. This tool is used to align the drum markings with the sight base reference point.

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