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3/7/2012 6:32:40 PM EDT
The bolt face on my DPMS LR260 has a ring of pot marks surrounding the firing pin hole.  DPMS says this is from gas blow by from the primer hole?
I have two AR15's, both have Bravo Co. uppers with BC bolts and the bolt faces are perfectly clean.  My BC uppers have shot thousands of all types of reloaded ammo and there is no sign of gas blow by from brass that was reloaded many times.  My upper is going back to DPMS and I was wondering if anyone has seen this before?  Maybe the bolt face was not properly hardened?  Any ideas?
3/7/2012 7:48:03 PM EDT
[#1]
I hate when they start to use pot metal for bolts
3/7/2012 8:48:58 PM EDT
[#2]
Is the tip of the firing pin pitted? If you've been piercing primers that could be causing erosion.
3/8/2012 4:28:18 AM EDT
[#3]
The firing pin looks good, no signs of a problem there.
3/8/2012 4:52:12 AM EDT
[#4]
Quoted:
The firing pin looks good, no signs of a problem there.


What kind of ammo have you been using in the DPMS?
3/8/2012 10:40:29 AM EDT
[#5]
If you are talking about the ring of carbon, then that does occur without issue in most AR's and it just needs to be cleaned off with some solvent and elbow grease.  If it is pitting or denting into the metal, then you need to send it back.
3/8/2012 12:47:11 PM EDT
[#6]
Quoted:
Quoted:
The firing pin looks good, no signs of a problem there.


What kind of ammo have you been using in the DPMS?


Mostly pulled Military 308 rounds, resized and I added new powder and bullet.  The original primer was used.  I always soak the warm bore and bolt with ballistol and water to neutralize and primer residue.  

3/8/2012 12:53:18 PM EDT
[#7]
If you shoot your guns a lot you will see a ring around the firing pin on most guns. As long as it's functioning properly I wouldn't worry about it.
3/9/2012 7:09:38 AM EDT
[#8]
Quoted:
If you shoot your guns a lot you will see a ring around the firing pin on most guns. As long as it's functioning properly I wouldn't worry about it.


I can live with a carbon ring which many of my pistols and revolvers have.  But a ring of craters?  I don't think so.
3/9/2012 8:43:44 AM EDT
[#9]
I had this happen on an AR-15 when I used the wrong primers for my reloads.  

Essentially, you are loading to higher pressers than that factory primer can handle, and the primers weren't meant for that pressure, thus the leaks past the primer of hot gasses causing the cratering.  Replace your bolt, and load using known components that can handle your higher pressure loads.

Here is a link that might help.
Link

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