Mossberg 930 Jam-O-Matic

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lbmii

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My new Mossberg 930 has been a Jam-O-Matic. With less than 50 rounds through it I have had many jams. Including a type of jam where the shell elevator/lifter gets stuck. The flaw seems to be inherent with the design.

I did a total cleaning and oiling when I first got it.

Any thoughts on how to get this shotgun to work as advertised? As it stands now I strongly discourage anyone from buying one.


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What kind of ammo are you using? What type of malfunctions are you experiencing? Some semi-autos won't cycle the target loads and require a more powerful load. I have heard of some 930's requiring a break in before they will run with lighter loads.

I have a 930 SPX. It functions well with everything I have put in it, including the bulk low brass and target loads. The only time I experience any issues is when the round count gets up to 250 without cleaning (cheap dirty ammo).
 
Did you disassemble the shotgun to clean it? I don't mean to insult your skills, did you reassemble it correctly?

Are you using the shells specified in the manual?
 
Did you clean and oil the gun before you shot It? Probably wouldn't be a bad idea to do so till it wears in.
 
Take the shell stop, bolt release out and clean all the crap out from behind it, lightly lube and run.

Factory magazine spring or extension? If it is extended, cut the spring to the correct length per the extension manufacturer recommendation.
 
A friend of mine was having the same problem with his. He was running Winchester 1 oz. 3 1/4 dram loads. When loaded with 1 1/8 oz 3 1/4 dram loads or heavier it works fine. I know first hand as the second time it went out I had looked it over and then witnessed the gun having issues. I ran it to see if it was something he was doing...it wasn't. When I fed it my ammo it ran flawlessly.

So back to the question...what loads are you using? As in shot charge weight and either dram equivalent or rated velocity. You may need to run some slightly stouter loads until it breaks in.

You already covered the cleaned and oiled part that previous posters may have overlooked.

Let me guess....some shells half out of the chamber and bolt locked back. Failure to eject and live one stuck underneath. Stove pipe on occasion. You are using 1 oz. loads or lighter and haven't tried it with heavier loads.
 
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Mine has not been flawless but works ok. The main thing that gets me is if I start playing with the lifter while walking around (shouldn't do that) it can catch on the bolt and I have to drop the trigger group to clear it.

I've never had an ammo related jam.
 
I just bought a 930 a couple weeks ago. I put 5rds of Winchester PDX1 (slug and buck) through it with no issues at all (didn't clean or lube it before firing - it was a display model, and had already been cleaned and lubed by the gun shop I bought it from).

Granted 5 rds isn't much, and the PDX1 loads are pretty stout, but so far I'm more than pleased with my shotgun, and before buying it I read a lot of good reviews and was advised that it's a great gun (as long as you don't get sand in it) before I bought it.
 
My 930 Rhythm shoots anything really well, we ran a couple of hundred rounds of mixed 1 and 1 1/8 oz. loads through it at a 3 gun shoot last month and it never hiccupped at all. My guess is some crud caught somewhere in it.
 
My 930 JM had a dent in the magazine tube that caused some serious problems. After I got that problem solved I still had to replace the follower to get it running well. The followers they come with are junk...

Sent from my HTC One X
 
I've bought several auto-loaders over the past few years. The steps I go through have proven to work 100% of the time.

1. Disassemble the gun. Not just take the barrel off. I take it all the way down, including taking the trigger group out.

2. Spray everything down with break free and give it a good scrub.

3. Put a light coat of rem-oil on all moving parts including the outside of the mag tube where the assembly is located.

4. Assemble.

5. I then head to the range with 40-50 rounds of heavy 3" waterfowl loads. I run those through the gun. I'll fire them pretty fast and let everything heat up and break in.

6. I then tear it down and give it a good cleaning.

7. After that, it should fire just about everything and anything.

Like I said, I've been doing it this way for years and has always worked.
 
In my first outing, all rounds fired were a variety of full powered buck shot Remington, Federal, and Estate. It did well with the Estate. All 3 3/4 dram buck of various sizes. I also did some 3 inch rounds. No low power rounds have been tried yet. I had several jams on the first outing. I recleaned and oiled it. Paid particular attention to the trigger group and lifter (wrong word). Orphanboy, I did not remove the bolt release and associated parts when I did the two cleanings. I will do this next. I do have a mag extension and adjusted the spring right away. The spring tension is firm but not too strong and I have no binding. I do not think it is a mag spring/mag issue at this time.

On my second outing I used 2 3/4" 1 1/4 lead Black Cloud ammo. It is hot ammo with a listed (and felt) velocity of 1500. I was very pressed for time in both outings. I did not document the jam types.

I think the next logical step is to do another disassemble. I need to check the shell lifter/elevator for any bends/rubs, the bolt release which I had not done, and I need to check for any burrs I may have missed. The mag tube seems good and without flaws.

Also I need to get some round through it. The second time out was better than the first. The problem is that I have little spare time in my life right now. This adds to my irritation of having to be a firearm company's quality control officer.

Hunterdad I will follow your words.
 
Hunterdad said:
I've bought several auto-loaders over the past few years. The steps I go through have proven to work 100% of the time.

1. Disassemble the gun. Not just take the barrel off. I take it all the way down, including taking the trigger group out.

2. Spray everything down with break free and give it a good scrub.

3. Put a light coat of rem-oil on all moving parts including the outside of the mag tube where the assembly is located.

4. Assemble.

5. I then head to the range with 40-50 rounds of heavy 3" waterfowl loads. I run those through the gun. I'll fire them pretty fast and let everything heat up and break in.

6. I then tear it down and give it a good cleaning.

7. After that, it should fire just about everything and anything.

Like I said, I've been doing it this way for years and has always worked.
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This is absolutely the best thing you can do with any new auto-loader. I follow this procedure myself. Most firearms manufacturers coat their guns with a preservative to help keep the metal from rusting before the gun gets to the customer. The preservative is NOT a iubricant and can easily contribute to malfunctions and jams until it is thoroughly removed and replaced with a light lubricant. The purpose of shooting the heavier loads is to quickly wear in whatever mating metal parts may be rough or less than perfectly fitting. Combined, the cleaning, lubing, and firing of heavy loads gives a new gun it's best opportunity to run reliably with all loads, especially light loads.
 
Any thoughts on how to get this shotgun to work as advertised? As it stands now I strongly discourage anyone from buying one.
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My 930 has run about 1K shells with nary a problem. It runs everything from magnum slug and buck to even the garbage winchester bulk ammo from walmart.

I hope you get your issues resolved.
 
The 930 has a pretty good reputation, but it appears they need some break in with heavier loads. Try some different loads and if that doesn't work, call Mossberg. They will take care of it.
 
5. I then head to the range with 40-50 rounds of heavy 3" waterfowl loads. I run those through the gun. I'll fire them pretty fast and let everything heat up and break in.
Click to expand...

I'll disagree about this being necessary - IF the gun is a quality-made gun and IF the required steps prior to firing were done correctly, then it should be ready to go with everything the owner's manual says it can handle. Gas guns, like pumps, do not have the same tight tolerances as a SxS or O/U (again from a quality maker), so "wearing in" should not be required
 
oneounceload... I agree that firing the heavier loads shouldn't be necessary, if the gun is properly finished and fitted. Proper fit and finish isn't something that can be relied upon, though, especially with the more economy priced models.

However, it does no harm to shoot heavier loads initially and should there be any spots where a little wear-in would be helpful, prior to shooting very light loads, shooting a couple of boxes of heavier loads should do the trick. I view the practice as just a little extra measure of "prep", just in case, though in most cases it shouldn't be necessary.
 
I have a 930 SPX. It functions well with everything I have put in it, including the bulk low brass and target loads.
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Same here, no issues. Have tried about 8 different loads through, and it has handled all with the same delightfully boring aplomb. Love it.
 
I saw one other report on this, there is a trigger disassembly tutorial on another shotgun site under the Mossberg section, go read it and disassemble and clean your trigger, it should fix the lifter problem. The shells not coming out of the magazine, try it with one less round each time you load up, if it holds 4, put in 3. If that cures that issue, the spring is too long.

Coworker just picked up a JM Pro and this solved both issues, I just got done putting it back together.
 
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