Mossberg 940 Pro Tactical Issues: A Troubleshooting Guide

Nov 14, 2025 by Alex Braham 58 views

Hey guys! If you're here, you're probably experiencing some hiccups with your Mossberg 940 Pro Tactical. Don't worry, you're not alone! This shotgun is a beast, but like any firearm, it can have its quirks. In this guide, we'll dive deep into the common issues, how to troubleshoot them, and some tips to keep your 940 Pro Tactical running smoothly. Let's get started!

Common Problems with the Mossberg 940 Pro Tactical

Before we jump into troubleshooting, let's identify the usual suspects. Knowing what to look for is half the battle, right? These are some of the most frequently reported issues with the Mossberg 940 Pro Tactical:

Failure to Feed: This is when the shotgun doesn't load a new shell from the magazine into the chamber. It can be super frustrating, especially during a competition or training session. This issue could stem from a variety of causes, including magazine-related problems, a dirty gas system, or ammunition incompatibility. Recognizing that this issue can emerge from numerous factors is the initial step toward successfully identifying and resolving the underlying problem.
Failure to Eject: This happens when a spent shell casing isn't fully ejected from the shotgun after firing. Imagine you're in a fast-paced scenario, and your gun jams because of this – not ideal! This problem can be triggered by numerous factors, such as an unclean or dry chamber, issues with the extractor, or utilizing low-powered ammunition. Pinpointing the precise reason is crucial for implementing the appropriate solution.
Failure to Extract: This is slightly different from failure to eject. Here, the shell casing is pulled from the chamber but doesn't make it all the way out of the gun. This issue often overlaps with ejection problems, but its root cause might be slightly different. Potential culprits include a compromised extractor, a chamber that's excessively dirty, or employing ammunition that doesn't align with the shotgun's specifications. To accurately address this issue, it's vital to discern the specific cause.
Light Strikes: This occurs when the firing pin doesn't hit the primer with enough force to ignite the shell. You might hear a click but no bang. A dirty firing pin channel, a weak hammer spring, or issues with the ammunition itself can lead to light strikes. Understanding these potential factors is essential for effective troubleshooting.
Gas System Issues: The 940 Pro Tactical is a gas-operated shotgun, so the gas system is crucial for its operation. A dirty or improperly assembled gas system can cause all sorts of problems, from cycling issues to reduced power. Proper maintenance and understanding of the gas system's components are key to preventing these problems.
Magazine Tube Problems: The magazine tube is where the shells are stored before being fed into the action. Issues here can range from dents and deformations that hinder shell movement to problems with the follower or spring. Keeping the magazine tube in good condition is important for reliable feeding.

Digging Deeper: Why These Problems Occur

Let's break down why these issues crop up in the first place. Understanding the root causes can help you prevent them in the future:

Lack of Maintenance: This is a big one! Shotguns, especially semi-autos like the 940 Pro Tactical, need regular cleaning and lubrication. Carbon buildup, fouling, and dried-up oil can wreak havoc on the gun's function. A consistent cleaning schedule is the bedrock of dependable performance.
Ammunition Issues: Not all ammo is created equal. Some loads might not cycle reliably in your 940 Pro Tactical. Using the wrong type of ammo or low-quality rounds can lead to failures to feed, eject, or extract. Testing different loads and finding what works best for your shotgun is a smart move.
Wear and Tear: Over time, parts wear out. Springs lose their tension, extractors can break, and other components can degrade. Regular inspection and replacement of worn parts are essential for maintaining reliability. Keeping an eye on the condition of your shotgun's internal parts can head off potential problems.
Improper Assembly: After cleaning or disassembly, it's crucial to reassemble the shotgun correctly. Parts installed backward or not fully seated can cause malfunctions. Always double-check your work and consult the owner's manual if needed. Correct reassembly is just as important as cleaning.
Factory Defects: While rare, sometimes a gun leaves the factory with a defect. If you're experiencing consistent issues even after proper maintenance and using the correct ammo, it might be a manufacturing problem. Contacting Mossberg's customer service is the next step in such cases.

Troubleshooting Your Mossberg 940 Pro Tactical

Okay, now let's get practical. You've identified a problem – what do you do next? Here’s a step-by-step guide to troubleshooting common issues with your 940 Pro Tactical.

1. Gather Your Tools and Supplies

Before you start, make sure you have everything you need. This includes:

Owner's Manual: This is your bible! It contains detailed instructions on disassembly, assembly, and maintenance.
Cleaning Kit: This should include cleaning rods, brushes, solvents, and lubricant specifically designed for firearms. A quality cleaning kit is essential for proper maintenance.
Gunsmithing Tools: A basic set of gunsmithing tools, such as screwdrivers, punches, and a nylon hammer, can be helpful for more detailed work. Having the right tools makes the job easier and safer.
Safety Glasses: Always protect your eyes when working with firearms.
Work Mat: A clean, dedicated workspace will help you keep track of small parts and prevent damage.

2. Safety First!

Before you even touch your shotgun, make sure it’s unloaded and safe.

Point the muzzle in a safe direction.
Remove the magazine.
Cycle the action to ensure there are no shells in the chamber.
Visually inspect the chamber to confirm it’s empty.

3. Diagnose the Problem

Think about when and how the issue occurs. This can give you valuable clues. Ask yourself:

When does the problem happen? Is it with every shell, or just some?
What type of ammo are you using? Is it the correct gauge and load?
Has the gun been cleaned recently?
Did the problem start suddenly, or has it been gradually getting worse?

4. Tackle Common Issues

Let's address some of the common problems we discussed earlier:

Failure to Feed

Check the Magazine: Ensure the magazine is properly seated and the spring isn’t damaged or weak. A weak spring can prevent shells from feeding correctly. Try loading fewer shells to see if it improves. Overloading the magazine can also cause issues.
Inspect the Shell Latch: The shell latch holds shells in the magazine tube until they’re ready to be fed. Make sure it’s clean and moves freely. A sticky or damaged shell latch can prevent proper feeding.
Clean the Chamber and Feed Ramp: A dirty chamber or feed ramp can prevent shells from entering the chamber smoothly. Use a chamber brush and solvent to thoroughly clean these areas. Carbon buildup can create friction and hinder feeding.

Failure to Eject or Extract

Clean the Chamber: A dirty chamber can cause shells to stick. Use a chamber brush and solvent to clean it thoroughly. Pay special attention to removing any plastic residue left by spent shells.
Inspect the Extractor: The extractor is a small claw that pulls the shell from the chamber. Make sure it’s clean, moves freely, and isn’t broken or worn. A broken or worn extractor is a common cause of extraction issues.
Check the Ejector: The ejector kicks the shell out of the gun after it’s been extracted. Ensure it’s in good condition and properly positioned. A damaged or misaligned ejector can cause ejection failures.
Try Different Ammo: Some ammo might not cycle reliably in your shotgun. Try different brands and loads to see if the problem goes away. Lower-powered loads might not generate enough force for reliable ejection.

Light Strikes

Clean the Firing Pin Channel: A dirty firing pin channel can prevent the firing pin from hitting the primer with enough force. Use a solvent and a small brush to clean the channel. Be careful not to damage the firing pin or its spring.
Inspect the Firing Pin: Make sure the firing pin isn’t broken or damaged. A bent or broken firing pin will not strike the primer correctly. Replace the firing pin if necessary.
Check the Hammer Spring: A weak hammer spring might not provide enough force to the firing pin. If the spring feels weak, it might need to be replaced. A gunsmith can help you with this if you’re not comfortable doing it yourself.
Try Different Ammo: Sometimes, the problem might be with the ammunition itself. Some primers are harder than others and might require a stronger strike. If you encounter light strikes only with certain types of ammunition, consider switching to a different brand.

Gas System Issues

Disassemble and Clean the Gas System: Follow the instructions in your owner's manual to disassemble the gas system. Clean all parts thoroughly with a solvent and brush. Carbon buildup is the primary culprit in gas system malfunctions. Ensure all gas ports are clear of obstructions.
Inspect the Gas Piston and Cylinder: Look for any signs of damage or excessive wear. Replace any worn or damaged parts. The gas piston is a critical component, and any damage can significantly affect the shotgun's cycling.
Ensure Proper Assembly: Make sure all gas system components are reassembled correctly. Incorrect assembly can lead to malfunctions. Refer to your owner's manual for the correct assembly procedure.

Magazine Tube Problems

Inspect the Magazine Tube for Dents or Damage: Any dents or damage can prevent shells from moving smoothly through the tube. If the tube is damaged, it might need to be replaced.
Clean the Magazine Tube: Use a cleaning rod and brush to clean the inside of the magazine tube. Remove any debris or buildup that could hinder shell movement.
Check the Follower and Spring: Ensure the follower moves smoothly and the spring has adequate tension. A weak or damaged spring can cause feeding problems. Replace the spring or follower if necessary.

5. Test Your Shotgun

After troubleshooting and cleaning, it’s crucial to test your shotgun. Use dummy rounds or snap caps first to ensure it cycles properly. Then, head to the range and test it with live ammunition. Start with a small number of rounds and gradually increase the number as you gain confidence.

6. When to Call a Gunsmith

If you’ve tried these steps and are still experiencing problems, it might be time to consult a qualified gunsmith. Some issues, like a broken firing pin or a severely damaged part, require professional attention. Don’t hesitate to seek help if you’re not comfortable working on your shotgun yourself.

Preventing Future Problems

The best way to deal with problems is to prevent them in the first place. Here are some tips to keep your Mossberg 940 Pro Tactical running smoothly:

Clean Your Shotgun Regularly: Establish a consistent cleaning schedule. Clean your shotgun after every use, or at least every few hundred rounds. Regular cleaning prevents carbon buildup and keeps the action running smoothly.
Lubricate Properly: Use a high-quality gun lubricant to keep moving parts running smoothly. Lubricate the bolt, rails, and other critical areas. Proper lubrication reduces friction and wear.
Use Quality Ammunition: Stick to reputable brands and loads that are known to cycle reliably in your shotgun. Using the right ammunition is crucial for consistent performance.
Inspect Your Shotgun Regularly: Check for wear and tear on parts like springs, extractors, and firing pins. Replace worn parts before they cause problems. Regular inspections can catch potential issues before they become major malfunctions.
Store Your Shotgun Properly: Store your shotgun in a case or safe to protect it from dust, moisture, and damage. Proper storage helps maintain its condition and prevents rust and corrosion.

Final Thoughts

The Mossberg 940 Pro Tactical is a fantastic shotgun, but like any firearm, it requires proper care and maintenance. By understanding common issues, troubleshooting effectively, and implementing preventative measures, you can keep your 940 Pro Tactical running like a champ. Remember, safety is always the top priority. If you’re ever unsure about something, consult a qualified gunsmith. Happy shooting, guys!