Firing Pin on AR15

clandestine said:

Pretty common issue. Superb job with your insepction.

Clean the bolts firing pin channel well. I like hot water and a degreaser like simple green for cleaning steel parts.

FWIW, if the pin isnt bent, you can lap the pin (dont touch the tip). Paint the pin with dykem or a sharpie and insert it into the bolt. This will show where the contact is when you remove it.

Apply jb bore paste or valve compound to the firing pin and work it in and out of the bolt. Clean the bolt and pin and recheck. Repeat until the pin can fall out of the bolt under its own weight.

Firing Pin Protrusion should be between .028 and .036.

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Xshot said:

Contrary to popular belief....Never. Ever. Touch the tip.

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whistlersmother said:

Didn't see any specific post/thread...

I have three of Del-Ton complete rifle kits - these come with assembled uppers and BCGs.

I decided to take Clandestine's advice and headspace check these - besides, its good practice at maintenance, etc.

While the headspace checkout out, after reassembling the bolt for one of the uppers, I noticed the firing pin didn't seem to "free float" very well. So, I took out the bolt and tried to push the firing pin through. At the very last 1/8", the pin became hard to push and had a "click" to get it seated all the way into the bolt.

All other firing pins slide in/out of the 1st bolt easily. So, it appears the problem is with the firing pin itself.

I'll be getting a new firing pin, but wondered how common it is for the firing pin to be machined poorly?

Also, one of the other bolts I have seems to have some type of grit/oil inside the firing pin channel. Looks like I'll be cleaning all three bolts and lubing them well.

Edit: Just wanted to add I haven't fired any of these uppers yet. Getting ready to try them out.

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judah7 said:

I wonder if I have a bcg issue, my firing pin is very stiff as well, and when you pull the trigger there's no boom alot of times.

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clandestine said:

That could be the firing pin binding or not enough protrusion. It could also be the cam pin, the hammer spring, headspace issues, or the hammer shaft binding on the lower.

KNS pins can also induce light strikes because they dont allow the pins to float as they were intended.

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judah7 said:

I wish I knew what you were describing so that I could check, I made a thread about this rifle here in this section, if it doesn't work tomorrow im going to meet up with a member and get some help diagnosing what's wrong.

All I want is for my rifle to work.

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whistlersmother said:

Thanks for the replies.

I did buy another firing pin - it falls in/out of the bolt on its own weight.

I will try lapping the troublesome pin. Its got a rough spot where it "catches".
I'll check the protrusion on all the bolt/pins also. We have simple green here somewhere...

I'm wondering if I would have gotten a slam-fire or no-fire with this pin...

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clandestine said:

Going to a shop?

May I ask the following about your gun?

What lower? Is it an 80%?
What Trigger Group is in it? Does it have a painted hammer spring"
Does it have anti rotation pins?




Yes, those were both possibilities, but no fire is more likely. Slam fires need other things to be wrong to happen with the lockup design of the AR.

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judah7 said:

It's a complete lower from new frontier armory, everything that's in there came from them, I do want to install a metal lower parts kit though.

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clandestine said:

They have plastic hammers that can lead to problems you describe. They dont have enough weight to reliably ignite primers.

Some hammers have to be fit to the NFA Poly Lowers because the pocket in the lower can be too narrow.

There could be other issues in the upper causing the failures to fire. Even things like the extractor can cause a gun to have problems going into battery.

Just make sure who ever is helping you really understands the gun well.

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judah7 said:

You aren't too far in Glen Burnie, would you take a look at it?

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