Firing Pin Sticks in FM9 Bolt

[RaylanGivens]

I have a newish Foxtrot Mike FM9 bolt and the firing pin has started sticking...  It acts like a broken firing pin, but the firing pin itself is not broken...  After removing the bolt from the rifle, the point of the firing pin is sticking out of the hole in the front of the bolt...  Pressing on the part of the firing pin sticking through the hole pops it up and it slides out normally.

 

I have about 1500 rounds on the new FM9 bolt and it never missed a lick until the last two matches I shot with it...  I remove the firing pin between matches and clean the bolt and firing pin with Hoppes 9...  Same as I have done with my other bolts...  Never had this problem before.

 

Curious to know what could cause this and what could be different in a FM9 bolt...  Any thoughts?

 

[WxGuy]

I also have a FM9 bolt, about 3000+ rounds on it now without a hiccup.  I figure it's time to replace the spring.  How many rounds on your bolt do you think you have?  Might want to email FM and see what Paul says.  

 

OOps, if I could read I would have seen 1500.

Edited July 27, 2020 by WxGuy

[stick]

What about the spring?  I would replace the spring and see what is does.  Shooting PCC, I know I have at least three extra firing pins and springs on hand.

[Dwbsig]

I would take some dial calibers and measure the tip in four or five places to make sure it don’t have any high places on it. 

[RaylanGivens]

On 7/27/2020 at 6:38 PM, stick said:

What about the spring?  I would replace the spring and see what is does.  Shooting PCC, I know I have at least three extra firing pins and springs on hand.

 

I keep several CMMG firing pins, springs, and cotter pins available...  They fit the Tacom and Iron City bolts I have using until now.

 

The outside diameter of the CMMG spring is too large to fit in the FM9 bolt...  The FM9 spring is a finer diameter wire and also wound closer to shaft of the firing pin so it will slide in fine...  Seems like the FP hole in the FM9 bolt is smaller than other bolts.

 

Anyone else ever have this problem?

 

[stick]

22 hours ago, RaylanGivens said:

 

I keep several CMMG firing pins, springs, and cotter pins available...  They fit the Tacom and Iron City bolts I have using until now.

 

The outside diameter of the CMMG spring is too large to fit in the FM9 bolt...  The FM9 spring is a finer diameter wire and also wound closer to shaft of the firing pin so it will slide in fine...  Seems like the FP hole in the FM9 bolt is smaller than other bolts.

 

Anyone else ever have this problem?

 

No.  I have the CMMG Firing pins and Springs too.  They fit my Taccom bolt and both of my PSA bolts.

[AHI]

At 1500 rounds you should be on your 3ed firing pin spring.

[RaylanGivens]

On 7/31/2020 at 8:07 PM, AHI said:

At 1500 rounds you should be on your 3ed firing pin spring.

 

You change your FM9 firing pin spring every 500 rounds?

 

I'm used to CMMG firing pin springs lasting over 2000 rounds...  The FM9 firing pin springs use a smaller diameter wire...  Maybe they don't last as long as I was expecting...  I can't believe no one has mentioned this firing pin spring issue on an FM9 bolt before.

 

[AHI]

why I no longer have a FM9 bolt. Any other brand change it at 5-7k rounds.

[RaylanGivens]

On 8/4/2020 at 8:36 AM, AHI said:

why I no longer have a FM9 bolt. Any other brand change it at 5-7k rounds.

 

I'm beginning to agree with you...  The FM9 bolt is functionally a nice bolt...  The trigger reset slope is good.

 

Unfortunately the small bore diameter of the FM9 bolts firing pin hole doesn't allow the use of standard AR9 firing pin springs...   Not sure why that decision was made...  The smaller diameter of the FM9 firing pin spring is unique to the FM9 bolt.