4 Common Mossberg 930 JM Pro Problems & How To Fix

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I recently had the opportunity to test out the Mossberg 930 JM Pro in the field. Let me tell you, it’s a gun that offers a whole lot, but I did run into a few snags here and there. 

Don’t get me wrong, the Mossberg 930 JM Pro is a solid shotgun, but you might want to watch out for a couple of things.

I came across four common Mossberg 930 JM Pro Problems while testing. We’re talking about failure to eject shells, magazine tube issues, feeding problems, and the occasional malfunction. 

Yep, even a gun as reputable as this one has its challenges. So, why not put together a helpful guide to address these issues? You know, sort of a roadmap to help you out.

Overview of Mossberg 930 JM Pro Problems & Solutions

Failure to Eject ShellsClean ejection port and replace weak ejector springs.
Magazine Tube IssueReplace magazine tube spring and check follower.
Feeding ProblemClean and polish feed ramp and claws; align if necessary.
General MalfunctionPerform thorough cleaning, replace worn parts, use high-quality ammo.

Top 4 Mossberg 930 JM Pro Problems & Solutions

1. Failure To Eject the Shells

So, while I was out on the range with the Mossberg 930 JM Pro, one issue that really got my attention was the failure to eject shells. 

There I was, ready to enjoy a good shooting session, but every so often, the used shell wouldn’t eject as it should. This is frustrating, to say the least, and it can really ruin your flow.

It’s like the shotgun’s ejection mechanism couldn’t quite give the shell that last push it needed to clear out. In technical terms, this could be due to weak ejector springs or a clogged ejection port.


Now, let’s get that sorted, shall we? What worked for me was first giving the ejection port a good 

cleaning. Sometimes, grime and debris accumulate, affecting the ejection process. 

For the weak ejector springs, a replacement did the trick. These springs are available from Mossberg directly or any reputable gun parts dealer. 

It’s a simple swap that takes about 10 minutes with the right tools. Since making these changes, I’ve had far fewer ejection issues, making my time on the range much more enjoyable. A clean port and new springs can make all the difference.

2. Magazine Tube Issue

Ah, the magazine tube issue. Another hiccup that took a bite out of my day at the range with the Mossberg 930 JM Pro. So, here’s the scoop: The shotgun’s magazine tube sometimes struggles with proper feeding. 

You load up your shells, but they just don’t make it up the elevator the way they should. On a closer look, it seemed like the spring within the magazine tube wasn’t delivering the right tension. 

It’s a critical issue because you can’t shoot if you can’t feed shells into the firing chamber.


Alright, so how do you fix it? In my case, the problem appeared to be with the spring. I replaced the magazine tube spring with a high-quality aftermarket one designed for this specific model. 

It’s a quick fix, and you’ll need just a few basic tools to open up the magazine tube, remove the old spring, and insert the new one. Make sure to check the follower as well; if it looks worn out, go ahead and replace it, too. 

After these tweaks, I got much smoother and more reliable feeding. There you have it—replace that spring and maybe the follower, and you’re back in action.

3. Feeding Problem

Ah, onto the feeding problem, another issue that I ran into while field-testing the Mossberg 930 JM Pro. You’re all set up, ready to take your shots, and boom—or no boom. 

The shell doesn’t feed into the chamber. It’s super frustrating, let me tell you. Sometimes, the shell would get caught or crushed before it could enter the firing chamber. 

The technical side of it suggests that the feed ramp or feed claws might not be operating as they should. They are supposed to guide the shell smoothly from the magazine to the chamber.


Now, the fix isn’t too complicated. What worked for me was giving the feed ramp and feed claws a good cleaning and then polishing them with some fine emery cloth. 

This helps reduce any friction that might be hindering the shell’s journey. If the issue persists, check the alignment; sometimes, the feed ramp may be misaligned, causing disruptions. A quick adjustment might be all that’s needed. 

I also used a lubricant suitable for firearms, but not too much, just a light coating. After taking these steps, the feeding problem became pretty much non-existent. Now, the shells feed into the chamber as smooth, and I’m back to enjoying my range time.

4. Malfunction

The last issue I want to talk about is a general malfunction problem. While out with the Mossberg 930 JM Pro, it was going all well, and then random malfunctions came out of the blue. 

I’m talking about misfires, erratic ejections, and sometimes the bolt wouldn’t lock back. For the life of me, I couldn’t initially figure out what was wrong. 

After diving into it, I found that general malfunctions can often be due to dirty internals, worn-out parts, or even low-quality ammunition. These things can mess with the shotgun’s reliability.


So, how did I tackle this? First things first, I did a comprehensive cleaning. Dirt and grime can often lead to malfunctions, so keeping the shotgun clean is a must. 

Next, I inspected any visibly worn parts, particularly springs and firing pins. If you find anything that looks off, go ahead and replace it. Finally, I switched to higher-quality ammunition. Trust me, it makes a difference. 

After these steps, the malfunctions dwindled down significantly. I wouldn’t say it’s bulletproof now, but it’s as reliable as it’s ever been for me. So there you go—clean, inspect, and choose good ammo. You’ll likely see a world of improvement.

Final Verdict

The Mossberg 930 JM Pro is undeniably a robust and versatile shotgun, perfect for both tactical and sporting use. 

But as we’ve seen, no firearm is without its flaws. During my time testing this shotgun in the field, I stumbled upon some common issues like failure to eject shells, magazine tube problems, feeding issues, and random malfunctions. 

Thankfully, these aren’t deal-breakers. With a bit of elbow grease and attention to detail, you can easily bring this shotgun back up to speed. 

In a nutshell, proper maintenance, timely replacement of worn-out parts, and the use of quality ammunition can make a huge difference. 

So, the bottom line is, if you invest a little time and care, the Mossberg 930 JM Pro is a reliable choice that will serve you well.


How reliable is the Mossberg 930?

The Mossberg 930 is generally reliable, especially when maintained well and used with quality ammunition.

What is the difference between jm930 and 940?

The 940 is an evolved version of the 930, offering a lighter weight and more advanced features.

Can Mossberg 930 shoot slugs?

Yes, the Mossberg 930 can shoot slugs and is known for its solid accuracy in slug-only areas.

What is the difference between Mossberg 930 JM Pro and 940 JM Pro?

The 940 JM Pro is lighter than the 930 JM Pro and comes with an extended ported choke, making it a more advanced option.

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I'm Micheal, an avid shooter and hunting enthusiast from Texas. I'm a recreational shooter who loves to spend time at the range and enjoy learning about new firearms and gears. I love to write about guns and share my passion for shooting with others.

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