My Mossberg Saga

OK, not really a "saga" and certainly not epic because I've only had the gun for a couple weeks. Still, it is an interesting story.

The gun worked flawlessly for 100 rounds. I was really excited about this new gun. Then it broke, but I didn't know it.

I went to fire some slugs and buckshot through it to test POI. The gun wouldn't feed from the mag. It acted like a single shot gun. It fired the shell, but the bolt would lock back every time and the next round would just sit in the magazine tube mocking me. The frustration prevented me from doing any real POI testing.

I made a video of what was happening:


The thing is, I'm a tinkerer. I can't stand it when something doesn't work and I just have to figure it out. I think God broke my gun so I would sit down and figure out how the stupid thing works.

The benefit is that now I'm an expert on how the Mossberg 930 works. I know how and why it holds or releases shells from the mag. I know what locks the bolt back and what releases it. I can now disassemble and reassemble the gun in my sleep with both hands tied behind my back, a blindfold on and using only my teeth. (OK, maybe that's an exaggeration.)

The good news is that I fixed it.

What I learned is the Forward Shell Stop wasn't moving far enough out of the way to allow the next shell to feed from the mag. So, I decided to polish it a little just in case it was hanging on the round in the mag. As I removed the Shell Stop assembly, I noticed that Mossberg had chosen to use two tiny pins to hold in the Forward Shell Stop rather than a through pin. This seemed very odd to me, but hey, I'm not a mechanical design engineer. They must know better than I, right?

The first round of polishing didn't fix it so, I went to remove it again. This time, the Forward Shell Stop went flying as I took it out of the gun. Grumbling about those two tiny pins, that I now have to find, I wondered again at that silly design. By a small miracle, and a magnet, I found the two incredibly tiny pins and attempted to reassemble the Shell Stop assembly. Then I noticed something else:



See those three parts the arrows are pointing to? Yeah, they should be one part. All my grumbling was for naught. They did design it with a through pin. I just didn't realize it because of the two broken ends.

A small drill bit graciously sacrificed its life to replace that pin. All is reassembled and the gun works perfectly now.

That's pretty ingenious. You have some tinkering skills.

You may not be a mechanical design engineer (greatly over-rated profession ), but you are a mechanical fixer (which is far more valuable ).

Job well done!

Nice fix. Your mission now is to explain why the pin broke in the first place.

LVSteve said:

Nice fix. Your mission now is to explain why the pin broke in the first place.

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The answer to this question I believe if lack of quality. I have not been around many Mossberg shotguns but 3 out of the 4 I have been around, broke. In 2 of these it was a pin like the op had. A nail was used in both cases to fix a pin that should never had broken as there was no stress on the pin. I do not know who supplies the pins to Mossberg, but I believe is time to try another supplier.

It is nice to see that the op is a man of action.

30-30remchester said:

The answer to this question I believe if lack of quality.

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This is the truth. I have never seen a pin break like this before. The only possibility is poor quality metal. I wasn't really surprised though. This is by far the cheapest shotgun I would consider. To make it this cheaply I'm sure they have to cut corners wherever they can. Thus, the metal this pin was made from was definitely second rate.

This particular pin does take some load. Not during firing, but it's under constant pressure from the springs and more when the bolt release is pressed. It takes a pretty good load when doing an emergency reload. When in a hurry, the bolt release is whacked to let that bolt go home.

Rest assured I'll be testing the durability of this fix in the near future.

30-30remchester said:

It is nice to see that the op is a man of action.

Click to expand...

Thanks for the compliment.

I absolutely HATE sending things back. Heck, I don't even like taking stuff back to the local store even if I can exchange it immediately. Can't do that with guns here in CA so, any return for repair is at least two weeks lost.

Since I like tinkering, it's nothing for me to spend a couple days trying to make a simple fix like this. It's good all the way around. I discover any potential weak points in the design and intimately learn how the thing works. This way I not only know my gun better, but can help others diagnose problems they may be having.

You should have got a Benelli M4 but nevermind

Now get one of these:

Mossberg 930 Tactical Bolt Release Pad -GG&G Tactica Accessories

Nice work.... you and I still have the same line of thinking ... in some areas.. . Fixing something ourselves instead of returning... love to tinker.... AND .... I just purchased the Mossberg JM 3-gun 930.... shot it yesterday for the 1st time... loved it shot great.

I had to have one, not because I shoot 3-gun, just liked the setup my buddy had. We went out shooting 2 weeks ago and he brought his Benelli special edition 3-gun he purchased from AR15.com... I liked the set up, just couldn't go for the $1400 plus price tag... got my JM 930 for $650 OTD..