Jerry & Lena-Mossberg 940 JM Pro Setup

Published on June 14, 2021
Duration: 10:17

This guide details how to adjust the stock of a Mossberg 940 JM Pro shotgun for optimal fit, a critical step for accurate shooting. Expert instructors Lena and Jerry Miculek demonstrate the process of modifying drop, cast, and length of pull using included adjustment kits. Proper shotgun fit ensures the shooter's eye aligns correctly with the sights, making the firearm an extension of their will.

Quick Summary

Shotgun fit is critical as your face serves as the rear sight. The Mossberg 940 JM Pro offers an adjustable stock kit to customize drop, cast, and length of pull, ensuring proper alignment for accurate shooting by seeing a flat rib with only the bead visible.

Chapters

  1. 00:09Introduction & Shotgun Fit Importance
  2. 00:58How to Check Shotgun Fit
  3. 01:28Visualizing Shotgun Fit Issues
  4. 02:16Length of Pull Adjustment
  5. 02:50Jerry's Shotgun Fit Preferences
  6. 03:43Lena's Shotgun Fit Preferences & Tools
  7. 04:43Safety Check Before Disassembly
  8. 04:59Disassembly of Buttstock
  9. 05:45Adjusting Stock with Spacers & Casts
  10. 07:05Reassembly of Stock
  11. 07:53Testing Initial Adjustments
  12. 08:44Correcting Missed Adjustment
  13. 08:55Final Fit Check
  14. 09:30Summary of Tunable Shotgun Features

Frequently Asked Questions

Why is shotgun fit so important for accuracy?

Shotgun fit is crucial because your face acts as the rear sight. If the stock doesn't align correctly with your eye, you'll consistently miss your intended target, similar to using a pistol with a loose front sight.

How do I check if my shotgun stock fits correctly?

Mount the shotgun and firmly press your face onto the stock. Observe the sight picture: seeing only the back of the receiver means your eye is too low; seeing the entire rib and bead high means your eye is too high. The goal is a flat rib with just the bead visible.

What adjustments can be made to a Mossberg 940 JM Pro stock?

The Mossberg 940 JM Pro features an adjustable stock system that allows for modifications to the length of pull, drop (rise/fall), and cast (left/right bend) using included spacers and plates.

What tools are needed to adjust a Mossberg 940 JM Pro stock?

To adjust the stock on a Mossberg 940 JM Pro, you will typically need a Phillips screwdriver for the buttpad and a socket wrench (often 3/4 inch) for the stock bolt. A drop of oil can also be helpful.

More Gunsmithing & DIY Videos You Might Like

More from Lena Miculek - Trigger Tribe

View all →