The Mossberg 940 JM Pro is a popular semi-automatic shotgun, prized for its reliability and versatility. One key aspect of its versatility lies in the ability to easily swap barrels, allowing you to adapt the gun to various shooting disciplines and hunting situations. This guide provides a comprehensive walkthrough of the Mossberg 940 barrel swap process, addressing common questions and offering helpful tips. Understanding how to perform a Mossberg 940 barrel swap correctly is crucial for maintaining your firearm's safety and performance.
Understanding Your Mossberg 940 Barrel System
Before diving into the swap process, it's essential to understand the Mossberg 940's barrel system. The 940 JM Pro utilizes a simple, yet secure, barrel mounting system. The barrel is not threaded, but rather utilizes a locking mechanism integrated into the receiver. This design ensures a tight and reliable fit while still allowing for relatively quick barrel changes. This is a significant advantage compared to shotguns requiring specialized tools or extensive disassembly for barrel swaps.
Key Components Involved in a Barrel Swap:
- The Barrel: This is the component you'll be removing and replacing. Mossberg offers various barrel lengths and configurations for the 940, including different chokes and cylinder bore options.
- The Barrel Extension: This is the part of the barrel that extends into the receiver and houses the locking mechanism.
- The Receiver: This is the main body of the shotgun that houses the action and locking mechanism for the barrel.
Step-by-Step Mossberg 940 Barrel Swap Instructions
Always ensure the firearm is unloaded and the chamber is clear before attempting any maintenance or modification. Double-check! Triple-check!
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Safety First: Point the firearm in a safe direction, and visually and physically confirm the chamber is empty. Engage the safety.
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Remove the Barrel: To begin, depress the barrel release button (usually located on the front of the receiver). While depressing the button, firmly grasp the barrel and rotate it slightly counter-clockwise. Once the locking mechanism disengages, gently pull the barrel forward and off the receiver.
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Inspect the Barrel and Receiver: Take this opportunity to inspect both the barrel and the receiver for any dirt, debris, or damage. Clean any residue found, using a suitable cleaning solvent and brush. Note: this is an excellent opportunity to conduct a thorough cleaning of your firearm.
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Install the New Barrel: Align the new barrel with the receiver, ensuring it is properly seated. Push the barrel firmly towards the receiver until you hear the locking mechanism engage with a distinct "click".
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Verify Secure Installation: Once again, visually and physically inspect to verify that the barrel is fully seated and locked. Gently try to rotate or pull the barrel to ensure it's secure.
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Function Check (Optional): Before heading to the range, consider running a few dry-fires (without ammunition) to confirm the action cycles smoothly with the new barrel.
Choosing the Right Barrel for Your Needs
Mossberg offers a variety of barrels for the 940, each optimized for different purposes:
| Barrel Length (Inches) | Choke Configuration | Ideal Use Case |
|---|---|---|
| 24 | Cylinder Bore | Home defense, close-range shooting |
| 26 | Modified | Bird hunting, sporting clays |
| 28 | Improved Cylinder | Versatile option, general purpose |
| 30 | Full | Waterfowl hunting, long-range shooting |
Note: Always check the Mossberg website or your owner's manual for the most up-to-date information on compatible barrels and choke configurations.
Troubleshooting Common Issues
- Barrel Won't Engage: Ensure the barrel is correctly aligned with the receiver. If it still won't engage, carefully inspect the locking mechanism for any obstructions or damage.
- Barrel Feels Loose: If the barrel feels loose after installation, it likely isn't fully engaged. Try removing and reinstalling the barrel, ensuring the locking mechanism clicks securely.
- Malfunction After Barrel Swap: If you experience malfunctions after installing a new barrel, ensure that the new barrel and ammunition are compatible.
Conclusion
Swapping barrels on a Mossberg 940 is a straightforward process that can significantly enhance its versatility. By following the steps outlined above and taking necessary safety precautions, you can confidently adapt your shotgun to various shooting situations. Remember always to prioritize safety and to consult your owner's manual for specific instructions and recommendations. Regular cleaning and maintenance will prolong the life of your firearm and ensure its continued reliable performance. Remember to check local laws and regulations regarding barrel modifications and ownership.