How tight should the firing pin fit into the bolt? AR .308

StevieP

StevieP

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Haven't been back to the range yet to re-test my .308 AR build.

You'll recall I had several failure-to-fire's with it last week. I wasn't sure if it was a light strike (under-powered hammer spring?) or something else. I took apart the BCG and cleaned & lubed it liberally (It's literally dripping wet).

In putting the BCG back together, I noticed that the firing pin doesn't just slide in & out of the bolt. It takes a bit of a 'shove' which I figure is probably normal, but figured I'd ask anyway...

If it's NOT normal, then that's perhaps why I'm getting light strikes. The hammer would have to hit the firing pin pretty hard to get it to shove the pin into the bolt far enough.

I compared it to the firing pin on my RRA AR-15, and there, the pin just slides in/out of the bolt with little (no) resistance.
 
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They should take it back no problem...did you clean it good after shooting?

I thought it might have been in the firing pin when i asked you last week if your firing pin had a spring on it. Never EVER would have expected the machining to be off though. Bad QC...
 
No It should not click, it should slide into place smoothly.
if you hold the pin above the bolt and release it should drop all the way to the shoulder of the firing pin.

It looks like either the hole in the face of the bolt or the firing pin is out of spec. (hole too tight or pin to large)
 
It's going back to Brownell's. The replacement is backordered. So I found a chromed one at Midway for only $4 more, in-stock.

I'd wanted the chromed one in the first place, but it was discontinued at Brownell's and I couldn't find it elsewhere. (not sure I'd checked Midway at the time...)
 
Ahhh. The new bolt & firing pin fit together properly. No binding, and the pin slides in easily until the 'shoulder' touches. Just the way it should.

The new bolt carrier is chromed, but the bolt and gas block are still "black." Interesting.

I'll report from the range asap.
 
Turns out it was a combination of things.

Replacement of the bcg didn't resolve it. Still got failure to fire even with a proper free-floating pin.

I swapped in the standard dpms trigger that came with the lpk, and took it to the range. Thirty trigger pulls, thirty 'bangs.'

So I'll save this POF trigger for a future AR-15 project. The mfg site does say not to use it in a .308 AR, but because it 'doesn't fit right in some dpms-pattern lowers.' Or, in my case it fit, but didn't work right. Not a heavy-enough hammer spring? Dunno for sure.

While this dpms trigger works, it's heavy, and a bit 'gritty.'

I sighted it in for 50 yards with the vortex strikefire red/green dot sight, and got good accuracy. I'll stretch it out next time.

Sent from my DROID BIONIC using Tapatalk
 

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