What would cause this

DUSTY NOGGIN

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Mar 18, 2015
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710
Location
salt lake city
It’s not fired just put in chamber closed bolt that’s what the primer looks like ejected
then you didnt bump .002 , or you did bump enough and pulled it back out on the upstroke

if your primers are touching the bolt face AT ALL when closing the bolt you are not doing something right , and with that scraping on the primer id say potentially at risk of an ignition before the bolt gets closed

im betting if you measure here and here with micrometers not calipers youll find a fourth pressure sign , this is likely the area not sized enough and binding enough to cause a swipe during a bolt close

20210115_220351.jpg


20210115_220331.jpg

can you clean and take a picture of your bolt face and , inspect the bolt lugs maybe get a better/closer picture of that same case head - your original picture looks like you rebuilt/reloaded a primer

if you set that brass on a flat surface primer down does it touch the primer
 
Last edited:

lancetkenyon

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Jun 3, 2013
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3,265
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Arizona
Did you clean the primer pockets before priming? Too much soot/carbon would cause the primer to not seat fully, then, with too little headspace or too much primer protrusion (more than .004"), you are basically crimping and deforming the primer with the firing pin hole in the bolt face.
 

GrayCreed

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Jun 17, 2020
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120
Location
Colorado
I have a Christensen arms elr in 6.5 prc and I am getting these marks on my primers. I put a resized case and primer no powder or bullet in the chamber and the bolt is really stiff. Any ideas
You are not touching the shoulder at all with your sizing die. When you squeeze the sides of the case the headspace grows if you haven't touched/or pushed back the shoulder .002"

I had almost the same problem with my 65cm I was trying to just neck size and the cases were coming out of the sizing die LONGER than they were coming out of the gun.
 

fraz01

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Dec 9, 2020
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82
Location
washington
Primer should be seated at least .002 below the case base. If the primer is below the base I would check the bolt face surface around the firing pin hole. If you pierced or have blown a primer you could have scoring on the bolt face. I would deprime the case and see if it is still tight. A tight case should not affect the primer unless it is seated shallow. Should be able to use the rod on a caliper or a straight edge on the base to check the primer depth. That load does look pretty hot with what looks like dual ejector marks.
 

TheLongRanger83702

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Feb 20, 2015
Messages
127
Location
Idaho
I have a Christensen arms elr in 6.5 prc and I am getting these marks on my primers. I put a resized case and primer no powder or bullet in the chamber and the bolt is really stiff. Any ideas
You need to use a primer pocket reamer on these cases to ensure there is sufficient space for the primers to get fully seated. This primer is sticking way out.
 

Saskquatch6

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Dec 2, 2012
Messages
32
Location
Saskatchewan
If it were me I'd be starting load development over from scratch - given all the signs of over-pressure (and we haven't yet mentioned the likelihood of loose primer pockets). Start with new brass (preferably) or once fired (that will chamber without first being resized and does not show any of the pressure signs mentioned) and use verified starting powder charges (published/manual) for the given bullet/powder combination. Check primer pockets and ensure primer is seated as mentioned in previous posts. If everything is in order I'd expect things to normalize and you can build your load from there watching closely for any pressure signs. Stop when any signs of pressure occur and back down your powder charge .3 to .5 grains from there. If a fired case from the new starting load will not chamber even after running through your resizing die then your sizing die may not be set up correctly or there is a mismatch between chamber and die (likely) meaning your rifle may have an undersized chamber and your sizing die can't sufficiently size the brass for it to chamber properly (had this issue with an early production Win Mod 70 - 300WSM). Good luck with this
 

brentc

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Joined
Apr 3, 2009
Messages
2,505
Whoo. That is a stiff charge! I can only run 60.4gr of N565 in a 6.5SS, which has quite a bit more case capacity.

There are a lot of guys operating in this area without caring about pressure. They just see a 156 going 3000+ fps and think they've got the world by the tail. Then they blame their pressure signs on everything but the powder charge. It absolutely has to be a carbon ring, right?
 

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