Mossberg 930 design flaw?

@O @oafpatroll 2 years ago

Also posted to GS

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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@D @ds-j

May I put this on the US shotgunsworld forum? They might have answers.

@O @oafpatroll OP

May I put this on the US shotgunsworld forum? They might have answers.

That would be appreciated D's J. I found references to the problem but not a definitive answer as to the cause or a final fix.

@D @ds-j

Answers from Shotgunworld:

" I have over 15k rounds through my standard 930 and no issues, the pin being shattered makes me think it is too hard/brittle and snapping instead of flexing some. drill stock is really hard, maybe try heating to red hot and then wrap in some fiber glass or something to let cool slowly. "

" More than likely, the pin was too hard causing it to snap instead of having some flex. A more suitable pin can be made from some spring steel pin stock. "

@O @oafpatroll OP

Answers from Shotgunworld:

" I have over 15k rounds through my standard 930 and no issues, the pin being shattered makes me think it is too hard/brittle and snapping instead of flexing some. drill stock is really hard, maybe try heating to red hot and then wrap in some fiber glass or something to let cool slowly. "

" More than likely, the pin was too hard causing it to snap instead of having some flex. A more suitable pin can be made from some spring steel pin stock. "

Thanks Ds J. The first one was the original and lasted a couple of hundred rounds while the second was made from a piece of drill shank that I tempered and it lasted for thousands. The spring steel pin stock idea is definitely one I'll try out.

@O @oafpatroll OP

A mate of mine suggested I try Redding decapping pins which are bang on the diameter of the holes. I expect that they will be a good match meterial properties wise. Have ordered some and will keep in reserve till/if the current one kicks the bucket.