Mossberg 500 missfires

P

phoreal

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Hi all,

I recently bought a used Mossberg 500, shoot's great however I'm getting about 3/25 misfires. When I checked the shells, quarter of the misfired shells seem lightly punched, while the others had a reasonable indent. I've been using Winchester and Challengers 2 2/4" target loads. Don't seem to have a problem with the 3" shells. Then again, I only went through a box of those. Could it be the size of the shells?

Took it apart, firing pin seems fine, couldn't tell whether it's short because I wouldn't know the OEM dimensions would be.

Any advice is greatly appreciated thank you.
 
Excessive Wd40 in the action will turn to a varnish over time and gets to be a pain to clean. Normal gun oil or g96 works great in mossbergs that see hard use
 
Maritime Storm said:
Which ammo is causing the problem?
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Both Winchester and Challenger at 2 3/4" shells

Greenhorse six said:
Could be gunk in the firing pin channel, give it a shot of WD40 or something like that.
If you need parts , as bybenn suggested , try western gun parts or Brownells for factory parts.
They're a easy gun to work on , just need a roll pin punch and small hammer, fo it right at the kitchen table. Lol
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When I took the bolt out, I didnt notice some orange gunk. If that's the case I'll give it a spray or drop of gun oil. Thanks for the advice. I'll let you know if it works when I take it out next time.
 
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Make sure your barrel is completely seated into the receiver and tight. This condition can lead to excessive headspace and light strikes. Pull the trigger group and check to see that the hammer spring is OK and has sufficient force. Hold your thumb over the hammer and pull the trigger to do this. Check for any debris while the hammer is forward. Last thing I can think of is make sure the safety is tight and not allowing the hammer to drag over it when firing.

Darryl
 
Change out your insanely stiff firing pin spring. Princess auto has a 101 piece spring kit and has almost an exact match with the one in your mossberg but WAY softer. Kit is like 7 bucks. Seems to be a common problem that the hammer spring sometimes isnt strong enough to overcome the firing pin spring to allow the pin to move forward enough to strike the primer effectively. The new spring is still plenty strong enough to keep the firing pin held back but not so crazy stiff as the OEM.



Original on the left, replacement on the right.
 
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53Izzy744 said:
Change out your insanely stiff firing pin spring. Princess auto has a 101 piece spring kit and has almost an exact match with the one in your mossberg but WAY softer. Kit is like 7 bucks. Seems to be a common problem that the hammer spring sometimes isnt strong enough to overcome the firing pin spring to allow the pin to move forward enough to strike the primer effectively. The new spring is still plenty strong enough to keep the firing pin held back but not so crazy stiff as the OEM.



Original on the left, replacement on the right.
Click to expand...

This is probably the fix you need.
I had the same issue with light strikes on my Mossberg 500. Took it the gunsmith and he swapped out the firing pin spring. It's been fine since.
 
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