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.264 LBC issue


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#1 OFFLINE   cmatera

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Posted Sep. 27 2017 - 01:17 PM

Been testing my .264 LBC BHW barrelled AR. Been shooting factory 6.5 Grendel 123 SST ammo, and not happy with the accuracy. Lots going on since I am shooting suppressed, adjusting the gas block and scope. I just noticed I have a couple of pierced primers. Where should I start diagnosing he problem? The firing pin, the bolt, or the headspacing?

#2 OFFLINE   GLShooter

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Posted Sep. 27 2017 - 02:24 PM

I change the firing pin and if no go call Hornaday. This isn't a new barrel is it?

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#3 OFFLINE   cmatera

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Posted Sep. 27 2017 - 02:36 PM

It is a new barrel. Been fired about 25 times. I measured the firing pin protrusion. I get .047-.048. Seems like a lot to me. I read guys getting .024.

#4 OFFLINE   GLShooter

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Posted Sep. 27 2017 - 02:45 PM

What's the bolt depth? Max protrusion is 0.036. Youmay have a parts issue. Maybe it's an enhanced 7.62X39 firingpin in a regular bolt.

Greg

#5 OFFLINE   cmatera

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Posted Sep. 27 2017 - 02:50 PM

.125

#6 OFFLINE   GLShooter

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Posted Sep. 27 2017 - 02:51 PM

See above.

Greg

#7 OFFLINE   cmatera

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Posted Sep. 27 2017 - 02:56 PM

I'll try changing the firing pin. If that doesn't work, I found a place that sells a bolt made for the 6.5 Grendel. Sound good?

#8 OFFLINE   cmatera

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Posted Sep. 27 2017 - 03:04 PM

Can I just order an ar firing pin or do I need one for the 7.62 x 39 bolt.

#9 OFFLINE   GLShooter

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Posted Sep. 27 2017 - 03:08 PM

Stick a standard pin in it and measure the protrusion. I've always just stuck standard pins in my 7.62 bolts. Never had a pierced primer at sane loading levels.

Greg

#10 OFFLINE   GLShooter

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Posted Sep. 27 2017 - 03:10 PM

I'll try changing the firing pin. If that doesn't work, I found a place that sells a bolt made for the 6.5 Grendel. Sound good?


No you cannot use a Grendel bolt in a 264 LBC. I will cause excessive head space.

Greg

#11 OFFLINE   cmatera

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Posted Sep. 27 2017 - 03:17 PM

Can I use a standard ar firing pin or do I need a 7.62 non enhanced firing pin?

#12 OFFLINE   GLShooter

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Posted Sep. 27 2017 - 03:25 PM

Can I use a standard ar firing pin or do I need a 7.62 non enhanced firing pin?



Try a standard one and see what you have for protrusion. Theenhanced are a tad longer to deal with the hard military primers.

Greg

#13 OFFLINE   cmatera

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Posted Sep. 27 2017 - 03:27 PM

Is the 7.62 firing pin the same as the 5.56?

#14 OFFLINE   GLShooter

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Posted Sep. 27 2017 - 04:00 PM

In this case yes.

Greg

#15 OFFLINE   cmatera

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Posted Sep. 27 2017 - 04:02 PM

Thank you

#16 OFFLINE   GLShooter

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Posted Sep. 27 2017 - 04:19 PM

Sorting these out can be a challenge. 95% of the piercing of primers is due to too much protrusion, a damaged tip, often seen because the pierced primer has left the tip jagged from the blow torch effect, or as been seen in the industry lately with Hornady and PPU the ammunition is at fault. In handloads we see this occasional from using primers that are too "soft" as in not thick, more than anything in concert with a sharp firing pin.  We round the later and replace the former.

 

Head space does not cause this issue. It may cause a blown primer but that's a totally different deal with other factors at work.

 

Greg



#17 OFFLINE   cmatera

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Posted Sep. 27 2017 - 06:45 PM

I have 25 rounds of that ammo left. I ordered a couple new ss firing pins. I think I'll start handloading now. I'll just disassemble those rounds for the brass and bullets. I don't want to ruin another firing pin if it's the ammo.

#18 OFFLINE   GLShooter

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Posted Sep. 27 2017 - 06:47 PM

Given a proper protrusion it shouldn't be a problem. I'd swap the pin, measure and shoot.


Greg

#19 OFFLINE   cmatera

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Posted Sep. 27 2017 - 08:23 PM

OK. I'll swap the pin measure the protrusion and shoot them up and go to reloading. Definitely a lot easier than disassembly to harvest the brass. I'd bet you hunch is correct and that 7.62 bolt came with an enhanced firing pin. That you for helping me sort it out and come up with a course of action
After dealing with the suppressor, adjustable gas block, scope and now this, my head was swimming. With weather and other stuff, I've been working on this project for a year and a half. Thanks again, you've helped me greatly.

Edited by cmatera, Sep. 27 2017 - 08:24 PM.


#20 ONLINE   gshayd

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Posted Oct. 08 2017 - 02:12 AM

This is on the .264 LBC barrrel page. You have a Grendel Type 1 and type 2.  Lots of Vendors are selling the Type 2 bolts and BCGs. I purchased my Type 1 from Yong Mfg I am pleased with it. It looks to be a very sturdy bolt.

 

"We originally made rifles with the standard head spacing (.125”) which we called type 1 and a second head spacing (.135”) only for the original Grendel which we called type II. Given the demand for standardization and lack of sales the type II head spacing has been dropped for 2017.


Edited by gshayd, Oct. 08 2017 - 02:19 AM.



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