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Thread: Mossberg 930 design flaw?
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19-01-2025, 19:59 #1
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Mossberg 930 design flaw?
I have an almost 10 year old Mossberg 930 SPX which I enjoy very much but for the two occasions when it has let me down due to parts breakage. There have been three of those with the first one being a broken extractor. I'll put my hand up for that one as at the time I was shooting a hell of a lot of unnecessarily hot heavy slug handloads through it.
The next two I think are the result of a flaw in the design. The part is a 1.55ish diameter 11mm long pin the connects the bolt release button/front shell stop (right hand side part in pic below) to the rear shell stop (left hand part). The first time it broke, about 8 years back or so, I replaced it with a piece of 1.5mm drill bit shank that I tempered in the oven. No idea how well the tempering worked but the pin lasted for many thousands of rounds and broke again on Friday night when I was getting in a last practice session before our clubs SADPA new years qualifier yesterday.
Stripped it yesterday afternoon and the pin was broken in three pieces exactly as before. Made up a few pins as before and once they had finished cooking I reassembled and tested with snap caps only for the f'n thing to break again. It was at that moment I realised I was a muppet as the fatter, shorter rear shell stop spring was in the parts bowl looking lonely. Redid the job and tested it out at the local indoor hell hole range and ran 50 shells through it in two shot strings all from the tube with an empty chamber which is the condition guaranteed to make it kak with the pin broken.
Given that the pin broke almost immediately on racking shells with a missing rear stop spring I wonder if its a bit weak. Anyone happen to have had the same thing happen or got any ideas? I'm fetching a pump action 12G I bought in 10 days time so this thing doesn't HAVE to do bump in the night duty after that but I'm very used to it and will take a good while to be as confident with the pump so I'd prefer to get it working reliably again.
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19-01-2025, 20:21 #2
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Re: Mossberg 930 design flaw?
Quick gOOgle search suggests you are not alone in this instance.. my 870 keeps on going.. swing by when you fetch your riot shottie
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19-01-2025, 22:17 #3
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20-01-2025, 09:41 #4
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Re: Mossberg 930 design flaw?
I wonder if it would last longer if made from spring steel?
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20-01-2025, 10:37 #5
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Re: Mossberg 930 design flaw?
Any chance of making the pin thicker?
Yes I now its not standard then, but like changing M 6 bolts to M 10 for extra strength.
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20-01-2025, 17:51 #6
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Re: Mossberg 930 design flaw?
A major problem I had with the RSA actions is the pin that held the bolt-stop/ejector would break regularly when made from hard steel like drill bits. One gunsmith recommended a 2mm brass brazing rod. That is still in one piece 6 years later.
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20-01-2025, 17:55 #7
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20-01-2025, 17:57 #8
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20-01-2025, 17:59 #9
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Re: Mossberg 930 design flaw?
Will see if I can get my hands on something in a usable diameter. Something in the 1.6m range would be good. As far as I can tell drill bit shanks aren't hardened as all the ones I've ever used for anything have filed easily. I understand it's to make then tougher and also to allow the chucks to bit which they don't so as well on hardened.
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20-01-2025, 18:12 #10
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