Jerry & Lena-Mossberg 940 JM Pro Setup

Published on June 14, 2021
Duration: 10:17

This guide details how to adjust the stock fit of a Mossberg 940 JM Pro shotgun, a process crucial for accurate aiming as shotguns lack a traditional rear sight. Expert Lena Miculek demonstrates how to modify length of pull, cast, and drop using included adjustment kits. Proper fit ensures the shooter's eye aligns correctly with the rib and bead, significantly improving shooting performance.

Quick Summary

Proper shotgun stock fit is crucial as the shooter's face acts as the rear sight. The Mossberg 940 JM Pro allows adjustments for length of pull, cast, and drop using its included kit. Achieving a sight picture with a flat rib and perfectly aligned bead ensures accurate aiming, significantly improving shooting performance.

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

How do you check if a shotgun stock fits correctly?

Mount the shotgun and observe your sight picture. Ideally, the rib should appear flat, and the front bead should be perfectly aligned without seeing the back of the receiver or the bead excessively high. This ensures your eye is positioned correctly relative to the barrel.

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

The Mossberg 940 JM Pro features an adjustable stock system allowing modifications to the length of pull, cast (sideways angle), and drop/rise (vertical angle) using included spacers and plates.

Why is shotgun stock fit so important?

Shotguns lack a rear sight, making the shooter's face act as the rear sight. A proper stock fit ensures consistent eye placement, allowing for accurate aiming down the barrel, which is crucial for hitting targets.

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

Basic tools are required, typically including a Phillips head screwdriver and a socket wrench (around 3/4 inch). A lubricant like Break-Free CLP-HP is also recommended for reassembly.

More Gunsmithing & DIY Videos You Might Like

More from Lena Miculek - Trigger Tribe

View all →