Firing pin or trigger spring?

Charlie Martinez said:

Could it be something else?

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I can always recommend a new mainspring. You cannot go wrong replacing a decades old mainspring with a new one. And, take a look at the breech face. Has the firing pin peened the barrel?. I have seen that cause misfires. I would recommend not only a new mainspring, but one of those new firing pins that Numrich sells.

Misfire problems can be due to headspace issues. If the bolt was swapped out the headspace may be excessive leading to a light firing pin strike. It will take removing the extractor's, firing pin, etc, and using a 22 lr chamber headspace gage to determine if you headspace is excessive.

Have yout tried different ammo, that was not in long term storage with the rifle?

My 144 Mosberg needs the slight gap in the bolt, or it will misfire. Why, i dont know.

My spring had worn the inside of the bolt where the spring moves. On firing the spring drags on the worn area. This slows pin velocity.
I fixed it by turning the spring around.

Headspace is another issue, but should not change while in storage. Firing pin protrusion , is another thing to check.

Charlie Martinez said:

Maybe I'm confused. Is the mainspring the spring that drives the firing pin forward? So, it is not the same as the "trigger spring". Is this right?
As far as I can tell the spring is very strong & doesn't appear to be damaged.

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Unless you know the compressive strength of a new spring and have a way to measure the old, you do not have a way to measure how much the old spring has taken a set. Springs loose their strength and somethings it is not as obvious as this:



I have replaced many old mainsprings and ignition always improves

What do you mean by "the bolt swapped out". Do you mean was the original bolt replaced with another?

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I am assuming that your Mossberg is one of the CMP Mossbergs that were sold. The CMP sold a lot of these Mossbergs, if so, that rifle has been through a number of hands.

If the bolt is serialized and is serialized to the receiver than you have the original bolt. If your rifle is a CMP Mossberg then you don't know if the bolt was removed, and another inserted. Happens all the time.

If the firing pin was worn would it not fire at all regardless of how many times the pin strikes the primer?

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I have had examples of firing pins shortening due to impact. Firing pin tips wear. I have replaced centerfire firing pins with one that had more protrusion to fix ignition problems.

I have a number of pictures of an broken Anschutz firing pin that I took at a Regional. I am going to say, if you can buy a replacement firing pin do so. If the original is fine, but breaks later, and you don't have a replacement you cannot fire the weapon. The fact Numrich has newly made firing pins makes me think this weapon breaks firing pins

Why or how would a gun that was perfectly OK prior to storage develop worn part issues while stored in a gun safe? I can see it developing cleaning issues but broken or worn parts seems illogical.

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I don't know the past history of your rifle. Did you buy it new? How many rounds have you put down the tube before it started misfiring?

But, even in the safe, mainsprings lose their tension because they are under compression. The M46 recoil spring had been sitting in a pistol since 1968 and that pistol had very few rounds through it before I got it. That pistol did give me misfires and squibs and I replaced the mainspring. Helped considerably. I have gotten to the point that the first thing I do when encountering misfires, squibs, with old guns is to clean the firing pin, the inside of the bolt, and insert a new mainspring.

As suggested, start by trying different ammo - normal storage should not effect mechanical performance but chemical performance (primer/ powder) may be effected.
If misfires continue (my guess), weak/ slow firing pin spring or firing pin just a tad too short from years of impact. Ammo is the best starting point - good luck.