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Is there an acceptable misfire % for the 500?

B

Bean

.22LR
Hello forgive my ignorance. I'm new to shot gunning.

2 years ago I bought a brand new in the box 500. Its for the cabin for bear/wolf protection.

Twice a year it goes to the range for practice, and other than a bore snake I have not cleaned it as my manual says to do so after 200 rds.

A few weeks ago it started misfiring about 6-8 out of 50 or so shots. I thought it was maybe the ammo as I tried out a new brand.

Yesterday I did a complete field strip and complete clean/degrease with some powder blast.

I didn't completely strip,down the bolt (got scared when one of the pins wouldn't hammer out) but,it got a thorough soaking.

Just got back from the range today and I still had 2 misfires out of 50 rds of buckshot, and 10 slugs.

I also retried 5 rds that didn't,go off last month. All fired except one.

What is an acceptable misfire,rate? I'd like to think zero. Bear vs slug, I,win. Bear vs misfire, bear wins.

If this is not acceptable then what is my next step? Warranty? (I have to pay shipping) or should a gunsmith take a look?

Should I just replace the bolt, and upgrade the trigger ? Upgrade the hammer spring?

File down something in the trigger assembly?

One,thing I did notice is that I cannot press the firing pin by hand so that it pokes out of the bolt. The spring is extremely tight. If I push the bolt down on a hard surface I can get the pin to poke out.

Should I replace the bolt spring, or maybe cut a bit of it off? Maybe take the washer out of the bolt?

I've read a lot on the web (maybe too much.)

Any thoughts?

Thanks
 
How do the primer strikes look on ALL your ammo that went thru a trigger press? Are the indents exactly the same across the board? Slightly different between ammo that went bang and ammo that went click?
 
I wouldn't recommend taking anything apart anymore than the two pins and the stuff that falls out of the receiver.

To the point of your question, there certainly shouldn't be that sort of problem in 50 rounds and lack of cleaning alone shouldn't cause that.

What ammo have you tried? Was the problem more common with one brand over another and I'll echo what NiteSite said, check the primer strike for differences.
 
I would also advise you to examine all the dents. Shoot some more and when you get misfires pull those shells, and measure the dent against the previous shell that fired correctly.

If you measure the depth with a dial indicator, and 10 different shells have 10 different readings, that would be normal within a certain range like 0 to 5 thousandths on the new gun and maybe twice that on an old gun.
But if you get several that there within thousandths, and one or two that were way off, like .030 or .050", that could indicate a short firing pin or a clogged action, or an action that is not closing to full battery.

It could be other things too, but those would be more dangerous and more obvious as well.

Since every new gun I have purchased the past year has had some rust on it, if you find that you have inconsistent firing pin strikes, and the firing pin feels too stiff, I would make sure it is 100% FREE from rust and any burrs from dull stamping or shoddy machining.

All that being said, I have been very disappointed in the quality of most all ammunition that I have bought lately.
 
I didn't look at all the ammo pin strikes. Only the misfires. There was indentation on all of them.

I have tried buckshot: federal wad control, Remington,reduced recoil, Remington "normal", and challenger. Also,challenger slugs.

The challenger buckshot had,the most misfires, and,regular Remington buckshot had a few.

I,attempted to disassemble the bolt but knocking out the big pin seemed to take a lot of force. I was bashing it very hard and didn't,want to break anything.

I guess it's off to a gunsmith to check everything over.

It's still under warrantydo you think it's worth sending,it in at my cost to ship?
 
Bean, If you have the luxury of 2 shotguns of the same gauge [I don't, but could borrow another] then go out w/ some boxes of ammo that are suspect and run a bunch thru both guns. If the known good gun has the same rate of misfires then suspect the ammo. If the known good gun has many fewer misfires then suspect your 500. Compare primer strikes, boom or no-boom. Keep records for further reference.

Good or bad, get back w/ us. We'll do what ever we can to help by remote control. :)
 
Just don't disassemble the bolt. Anything beyond what easily comes apart will void the warranty. Quite possibly even by a gunsmith unless he or she is certified OFM and I don't know that there is such a thing.
 
Haven't shipped the shotgun yet.

I've heard of some guys removing the firing pin completely. Would this actually work?
 
I have had misfires with Sellier and Bellot rounds (with my Mavericks/500s), but that was the only brand. That is just my experience, though. I have not bought any of those brand rounds, since. With my Stoeger Uplander (double barrel) I have had Remington Sluggers fail, every time. They fired fine out of every other shotgun I have. As I say, just my experiences. Take care. Tom Worthington
 
@Bean Have you soaked and cleaned the trigger assembly also ? Could be a weak or broken hammer spring???
 
It can be a lot of different things.

weak hammer spring is the most common culprit. While after 200 shots fired, the trigger group will probably be fouled, but I wouldn't think it would be concreted together.

You can take the entire trigger assembly out of the gun as a whole piece and spray it down good with brake cleaner or wd 40 or pb blaster or whatever you have without having to take everything apart. It's pretty tough getting everything back together if you start taking everything apart separately and there is really no need, so it's usually much easier to leave it together and spray it down that way.

Hard primers could be a possibility, shells that have been stored in poor conditions or that have been wet or exposed to long term moisture (like what can happen in a cabin or damp basement), could also be coming into play.

If you had a no-fire, did you try to run it back through the gun to see if it would fire the 2nd time through?
 
Acceptable rate is ZERO. I am not sure of Mossberg's warranty policies, but I'd sure give them a call. It doesn't sound right to me.
 
Acceptable rate of misfire is zero. I think your best bet at this point is to ship it back to Mossberg. Sure, you have to pay shipping, but its probably less than paying a gunsmith, who may or may not fix it.
 
Just an update, and answer some questions.
John, I did try to retire the misfires shells and 3 out of 4 did fire,the,second time.

I was able to remove the firing pin/spring. Everything was clean as a whistle, and smooth, no burrs or anything.

I haven't "blown" out the trigger assembly. I could do that. Actually I ordered the metal trigger assembly that has beefier springs in it.

I did notice the firing pin spring is extremely stiff. I mean real stiff. Stiff as in the firing pin cannot be pushed by hand.

Now that Christmas is done I will probably just send it in for warranty service.

Will they tell me what the problem was, or just give me back a working shotgun?
 
They probably won't give you exact details on what was wrong, but more than likely they will tell you what parts they replaced or adjusted. But I'm like you. Really curious as to what's causing the misfires. My guess is they will replace the bolt and/or the hammer spring.

Please keep us updated.
 
Ok time for an update. I swapped out the stock trigger group for the all metal version, so essentially I replaced the hammer spring. It is noticeably "stiffer" when I rack the slide.

I am happy to report that I fired off 60 rounds of buckshot, various brands, and 20 slugs.

Not a single misfire! I'm pretty confident it was a weak hammer spring at fault.

I've also replaced the hammer, and trigger spring in the original trigger group. I didn't bother trying out as I was happy with the new trigger, and my shoulder was starting to complain after 80 rounds, which came after 50 rounds of 308.
 
Point of interest.... the hammer spring in the metal trigger is actually two springs! A smaller spring inside the larger spring.
Pretty impressive.
 
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