Mossberg 500 misfires

[BeerThirty]

Went to a buddies house over the weekend to do some plinking. Have some 12-gauge buckshot and wanted to pattern it at variable distances. Honestly, never even shot buckshot before so was just intending to have some fun and learn.

Well, I used my old Mossy 500 pump, first gun I ever bought when I was 10 or 11. Has a born on date of 1990 and was heavily used for maybe 6-8 years, but always maintained. Frankly, use has been fairly infrequent over the past 20 years other than an occasional box of shells here at there.

Anyway, the first two shells did not fire. Firing pin dropped and dented the primer, but did not ignite. 3rd shot did. Shot a couple birdshot just to test and they all fired. I'm guessing it's the shells? These are Sellier & Bellots. I've had great luck with the brand on other types of ammo, but first time I've used their shells.

You think it's the shells, or firing pin (old), or both? I'm assuming there's a spring that can be replaced in the firing pin?

 

[Gator89]

Went to a buddies house over the weekend to do some plinking. Have some 12-gauge buckshot and wanted to pattern it at variable distances. Honestly, never even shot buckshot before so was just intending to have some fun and learn.

Well, I used my old Mossy 500 pump, first gun I ever bought when I was 10 or 11. Has a born on date of 1990 and was heavily used for maybe 6-8 years, but always maintained. Frankly, use has been fairly infrequent over the past 20 years other than an occasional box of shells here at there.

Anyway, the first two shells did not fire. Firing pin dropped and dented the primer, but did not ignite. 3rd shot did. Shot a couple birdshot just to test and they all fired. I'm guessing it's the shells? These are Sellier & Bellots. I've had great luck with the brand on other types of ammo, but first time I've used their shells.

You think it's the shells, or firing pin (old), or both? I'm assuming there's a spring that can be replaced in the firing pin?

If the gun shoots other brands of shells, then I would say it is the shells.

There is not much that can go wrong on a Mossberg pump.

 

[BeerThirty]

If the gun shoots other brands of shells, then I would say it is the shells.

There is not much that can go wrong on a Mossberg pump.

Thanks. That was my assumption but I was toying around with the idea of just putting in a new spring or firing pin just to eliminate any possibility.

 

[earlthegoat2]

If the ammo switch proves to to work long term…

Take out the bolt assembly and thoroughly spray it with brake cleaner or something like gun scrubber. Then blow it out with compressed air and then relube.

Do the same to the trigger assembly but use something milder so as not to mar the plastic.

Replace the hammer spring if problems persist.

 

[bighonkinjeep]

Has it ever been sprayed with WD40?
There are several products that can leave behind unwanted residues, gum and varnish over time. WD 40 is one of the worst.
Just because of time I think I'd start with a good cleaning and lube with Breakfree CLP and go from there. Also be sure the barrel is fully seated and the retaining cap tight. Maybe also try the duds again or in in another shotgun and see if they go boom.
Good luck.

 

[specialk]

id clean it first anyway, aint gonna hurt...

 

[BeerThirty]

Has it ever been sprayed with WD40?
There are several products that can leave behind unwanted residues, gum and varnish over time. WD 40 is one of the worst.
Just because of time I think I'd start with a good cleaning and lube with Breakfree CLP and go from there. Also be sure the barrel is fully seated and the retaining cap tight. Maybe also try the duds again or in in another shotgun and see if they go boom.
Good luck.

Never WD. I only clean with solvent and RemOil. Thanks for the tips.

 

[BeerThirty]

id clean it first anyway, aint gonna hurt...

Yeah, you're right. I think a deep, deep clean is probably due.

 

[furtaker]

I bought a cheap Maverick 88 field model (same action as a 500) a while back and it started misfiring immediately with Winchester buckshot. Light primer strikes right out of the box. The second shot would go off.

Sent it back to Mossberg and it was still misfiring when I got it back. Sent it back a second time and they replaced the bolt.

It didn't fix it. It still misfires on occasion with Winchester shells.

 

[rosewood]

Could be gunk in the firing pin channel, the thorough cleaning may take care of it.

Rosewood

 

[bullethead]

Never WD. I only clean with solvent and RemOil. Thanks for the tips.

Remoil, if left on long enough, will evaporate and leave behind a similar varnish. I found that out years ago after using it for a good number of years. I had thoroughly cleaned the innards of two S&W 629s and put them away. They sat about 6 months and the hammers were extremely hard to ck back. The insides had a brown gum coating. And I am not one to overlube.
The aerosols require a carrier and propelant to get the product out of the can. The carrier/propelant are supposed to evaporate away and leave the product behind. The process evaporates some oils also. Some oils and lubes are more affected than others and in my experiences Remoil has been one of them.
Ballistol and Kroil aerosols have been great for me. Otherwise I use non aersol oils and lubes.

 

[tcward]

Replace the firing pin and spring with an aftermarket (not Mossberg). A Rowe Tactical should work well.

 

[B. White]

My daughter has my 90s 500 and wanted to shoot it last year. Did not go bang on a couple. Worked perfectly for me. Watched her and the only difference was she didn't pump it with authority. No more issues once it was pointed out to her.

 

[bullgator]

Sound like a lazy firing pin probably due to gunk buildup. The first two attempts probably just helped get it cleared and moving enough to start hitting hard enough to ignite the primers. A good cleaning will probably fix it.

 

[tr21]

My daughter has my 90s 500 and wanted to shoot it last year. Did not go bang on a couple. Worked perfectly for me. Watched her and the only difference was she didn't pump it with authority. No more issues once it was pointed out to her.

my brother and I have 4 835's we've both had trigger jobs done on 1 of them. he had a turkey dead to rights and it went click ! we took it out and found out if you don't shuck that 1st shell in hard his would sometimes not fire, mine has never done it, so I think this is the answer

 

[furtaker]

my brother and I have 4 835's we've both had trigger jobs done on 2 of them. he had a turkey dead to rights and it went click ! we took it out and found out if you don't shuck that 1st shell in hard his would sometimes not fire, mine has never done it, so I think this is the answer

You're right that it could be but that's not necessarily the case. I make doubly sure to close the action tight on my Mossberg I've had problems with and it will still misfire sometimes. So far it's only been with Winchester shells.

There's been lots of talk on the web about Winchester Long Beard shells misfiring in 835s.

 

[tr21]

You're right that it could be but that's not necessarily the case. I make doubly sure to close the action tight on my Mossberg I've had problems with and it will still misfire sometimes. So far it's only been with Winchester shells.

There's been lots of talk on the web about Winchester Long Beard shells misfiring in 835s.

we shoot the custom Nitro's, not Remington's in our 835's.

 

[NCHillbilly]

I have never had a single misfire in my 500, and it's been shot thousands of times over the decades. It even shot a 16 gauge shell once that I accidentally jacked into it.

 

[Robert28]

When you sent it in did they check or change the firing pin spring by chance? I don’t know about now but that seemed to be a common thing with the 500’s back several years ago. Don’t know if they ever had a recall or not but I did a quick google search of “Mossberg 500 firing pin problems” and pulled up all sorts of threads describing what you did.
I don’t think it’s a gunk problem, I’ve had muddy water get in my 870 and it kept on ticking. Firing pin spring, I’d start there if it was me. I’ve never owned a 500 before so I don’t know them inside and out like I do the 870’s.

 

[trial&error]

Probably just hard primers. The selection of S&B ammo is exclusively price related or in recent times availability. A good cleaning of your gun is probably a good Idea in general and for many of us long over due.