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Mosberg 930 issue


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Hello all! I'm new to the board and have gotten my gear together to start shooting 3gun but can't seem to get the shotgun part going. I purchased a brand new 930spx to use as a platform for a 3gun shotgun a couple of months ago. Right out of the box it has problems (gas cylinder was binding on the mag tube and barrel would not come off the gun). Called Mossberg and they sent a call tag, picked the gun up and had it back in a couple of weeks with a replacement barrel and mag tube (original not the extended). At the same time I order a 24" non ported barrel. I get the gun back and the new barrel and head out to shoot and it fails to function with the new barrel.. Arg!

What is happening now is the bolt will go forward and meet the breech face OK but when I pull the trigger its...click.. I hear the hammer dropping but not firing. I now see that the piece inside the bolt that cams up into the barrel is not locking into place. I can push the charging handle forward and it moves forward in the slot slightly and you hear the part click and lock in the barrel. The bolt itself stays in place its the part inside and the bolt handle that moves. It will then fire but the next shell that cycles does the same thing..push the bolt and fire and then the same thing again.

Any idea whats going on here? I called Mossberg and they want me to send it back to them but this time its my dime for the shipping! And.. the gun is gone again so its going to delay shooting in my first match again! I've missed 3 already waiting on this gun to work since October! Its well lubed too...

Thanks

Joe

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Great link! Thank you. That gives me a starting point as this seems to be that exact problem! The only thing that concerns me is that unless Mossberg fired the gun while they had it, its only had 2 boxes of shells fired through it by me and that was all the bang click deal. I need to see how to disassemble the piston ring and get it back together correctly!!

Joe

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Well back from the range... not so good.. I have that gas piston clean as a whistle and the barrel is new but I cleaned it anyway. No change. The bolt still fails to lock up. I still have to bump the handle to get it to lock. I took it apart at the range cleaned an re-assembled but no change. 2 or 3 times it did actually fire the second shot but that was out of 25 shells. I watched that video and have the rings oriented correctly. I'm stumped and hate to have to pay to ship this gun to Mossberg..

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Its the federal 2 3/4 3Dram 7 1/2 size shot. They work in my Beretta 391 Sporting, Remington 1187NP Sporting and my regular 1187 hunting gun and are pretty stout. That's also frustrating, I have several flawless auto shotguns but this one is is giving me fits!!!

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Joe,

My 930, and many others, cycled anything right out of the box.

I do recall reading that some needed a box or 2 of heavy loads before they started shooting anything.

Just thinking out loud here, I wonder if the SPX is different(recoil spring) because of the expected shells it would normally see like buck or slugs.

Maybe Benny Hill will chime in.

David E.

Edited by Nuke8401
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Joe,

This is one of the best reviews/test of the 930 SPX. Not all of the info applies to 3GUN but much good info including the quote below.

My link

As another point of information, it helps to clean the SPX well before you shoot it for the first time. Mossberg seems to on occasion have a lot of preservative or fouling in their shotguns in them, and some people have had issues with malfs due to not cleaning their new SPX shotguns. Additionally, your SPX may be ammunition sensitive at first. A lot of shooters have had problems using slower/lighter shot loadings cycling their new SPX. Using heavier (above 1300fps) loads at first and then transitioning down to lighter loads seems to work for those that had ammunition issues.

I've had one stovepipe on some old (probably 10 years) low-brass WalMart light loads among all the different types that I've shot, and that has been the extent of ammo sensitivity on my SPX.

----------

Make sure the mag tube spring isn't too long. If it is, it will prevent the first round from being released from the mag tube if the mag tube is at full capacity.

Take the barrel off and look at the spring on the gas piston. You should be able to see it in the witness hole. The first gen springs were blue, and there were some that were black. The newer springs are red. They will let you shoot lighter loads, although some (including myself) never had a problem with lighter loads with the blue and black spring.

Make sure you clean it well. I mean really, really clean. Mossberg ships their shotguns with a ton of preservative in their shotguns.

So maybe a good cleaning of the entire gun is needed including the gas ports in the barrel.

David E.

Edited by Nuke8401
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Nuke, Very interesting review. One thing I zero'd in on is: "The first gen springs were blue, and there were some that were black". The new (problem) barrel is a 24" non-ported Turkey barrel with a blue spring. The SPX barrel that functions fine has the black spring. I'm not sure what the difference is but the article leans toward the blue being a stiffer spring.

Is it possible that the blue spring is too stiff and not allowing the bolt to close fully, thus forcing me to have to push the bolt handle closed? I'm not a gunsmith or engineer so why would a stiffer spring in the gas cylinder be an issue? Shouldn't it be the recoil spring in the stock that relates to stronger loads like "Turkey" loads?

Joe

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I was wrong, just took the 930 down to parade rest will post some photos and video later.

David E.

The spring at the gas piston does not touch or move the piston directly. The spring holds a single gas ring in place that I suspect acts to relieve pressure out of the visible ports when the piston cycles.

Edited by Nuke8401
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I can try and clean it more but this gun only has 3 boxes of shells fired through it by me and the 24" barrel is brand new custom order from Mossberg its really spotless other than the fouling that I did yesterday.

After thinking about what you said about me have it backwards, that may be making sense about the spring in the gas cylinder. Since the piston doesn't travel far, a stiff spring in there may be retarding the piston on the return enough to slow the bolt and not let it lock up. Even though the loads are kinda standard run of the mill they are no where near as stiff as Turkey loads that this barrel is designed for. Any fouling could compound the issue.

So that spring looks like its not for the faint at heart to replace and I'm not sure Mossberg would sell me one! I'm guessing that this may need to go back to Mossberg or Wheaton Arms is local. I was at the last local 3gun match and a guy there was shooting a tuned 930 with a Turkey barrel that Wheaton arms had put together and was working.

I wonder if anyone has had trouble like this with a Turkey barrel?

Joe

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I only have the one piston. Its the one that came with the SPX. The 24" Turkey barrel did not come with a piston. When I put the SPX barrel on it works. When I put the Turkey barrel on it stops working and fails to lock up. That would have been a good thought as that would have eliminated or pointed the finger at the piston as the culprit!

Joe

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When I put the SPX barrel on it works. When I put the Turkey barrel on it stops working and fails to lock up. That would have been a good thought as that would have eliminated or pointed the finger at the piston as the culprit!

I sure would like to know if there is a difference in gas port size between the SPX barrel and the turkey. I would expect the length of the turkey to generate more gas/pressure than the SPX. I wonder of the combination of a possibly heavy SPX spring with the turkey barrel is the problem?

I could see where Mossberg might have reduced the gas port size on the turkey compared to the SPX to limit gas.

Or possibly the bolt fit to the turkey barrel.

Or it just needs a bunch of shooten!

End of my knowledge.

David E.

Edited by Nuke8401
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All good questions! I was thinking that maybe the action spring in the stock was set or tuned with the spring in the gas cylinder for certain guns. I'm mixing and matching and its not working! Maybe I do just need to gets some really smokin hot loads and just manually crank those out in the gun and see it anything changes.. Thanks!!!

Joe

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Run a box of 3 inch thru it then try something lighter. I know when I had my 18 inch barrel it wouldn't run fiocchi low recoil buck, put the 28 on it and it would. There could be a gas port size difference.

The turkey barrel could have smaller ports and isn't pushing enough gas.

Sent from my PG06100 using Tapatalk

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OK took my 930 apart.

12-21-2011020.jpg

You can see the single gas ring then the spring then the retainer. The spring holds the gas ring in place. I think when the gun fires gas pushes this ring forward allowing gas to escape from the external ports. I would guess this is to limit the gas going to the piston. My spring is red. I made the bolt compressor to get it back together.

12-21-2011022.jpg12-21-2011021.jpg

So a stiffer spring here would only increase the gas to the piston and cycle the bolt harder/more recoil.

The video shows cycling the bolt with the trigger mechanism removed. It looks like the only thing moving the shell stop out of the way to allow a shell in the receiver is the spring on the latch itself.

http://www.youtube.com/watch?v=2kpbRX_PiqI

So I would suspect that replacing the shell stop spring pc. 21 with a stiffer spring would fix the hand cycling issue. It may cause faster wear between the slide assembly and the rear shell stop.

Maybe someone like Nordic could make a slightly stiffer spring.

Just some more info.

I see no reason to remove the spring again, kind of a PITA to get back in.

David E.

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Oh man! That spring looks harder to take apart than the one on my Beretta 391! I think I may just have to suck it up and send it back to Mossberg and let them fool with it. Disappointing! I wish this had been easier to get running and not a frustrating experience! Thank you all for helping me!!! I'll report back when I get it running or if I find anything else.

Joe

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I just developed the same problem. :wacko:

I have a 930 waterfowl build, cut to 22", +4 Nordic that I have run hundreds of Walmart bulk pack Federal Multi 2 3/4 3 DRAM 7 1/2 through without issue until last week.

The 930 was cleaned and lubed right before my last match, ran maybe 80 rds through it without any issue at the match and then it was put back in the safe.

Went to the range a few days later and immediately had cycling issues, same ammo and no changes from my match a few days prior where it ran 100%.

First round fires, bolt goes foward but stops just short of going into battery and I get a click instead of a bang.

If I fire a round I have to assist the bolt foward into battery then it will fire the next round and I have to repeat that process every time.

I came here looking for help as I have not been able to take it apart and troubleshoot it yet and it looks like a few others are having a similar problem but with varying round counts.

I am going to clean it and focus on the piston assembly but I feel like there may be something else going on especially since others have cleaned and lubed without fixing the issue, any other ideas?

Edited by deltabravo555
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Deltabravo, In my case I'm leaning toward the spring in the gas cylinder. Maybe not so much the rate as the alignment of the ring in front of the spring. In my case It could be a combination of both. I put my piston and original SPX barrel on today and went to the range and it functioned 100% with a box of the same shells you are using. While there put the 24" non ported turkey barrel on and using the same piston its a no go. Are you getting any scoring on your mag tube around the cylinder area? While changing my barrel today, I'm noticing some scoring and a partial line that may be lining up with that ring on the spring side of the gas cylinder...

Joe

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