Annoying pressure issues

Steelshooter842

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Dec 14, 2018
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After dealing with excessive pressure I decided to seat my bullets deeper and reduce the charge. I did a ladder test and got a good node so I loaded up 50 rounds for my 260 rem, new lapua brass, 39.9 grains Rel 16 and 147 grain ELD match. They were pretty accurate but 2 of the 50 cases had ejector marks on the base and less tight primer pockets. The other 48 rounds were fine. While I can live with 2 out of 50 I still can't figure out whats going on here. Anyone have a theory.
Thanks
 

whatsupdoc

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I am assuming you are getting a round ejector plunger mark on the base of the case.
Are you getting shiny swipes? Post some close clear pictures.

It could be you have no pressure issues but the ejector hole in the bolt head has a raised sharp edge causing the mark.
 

Steel head

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While I run much roomier brass and a long oal in my 260 I’m well over your load with R16 and 147’s.
Are your case marks smeared or a clean circle.
As said above a sharp ejector cutout along with possibly a slightly short case could easily make marks that look like pressure.
 

Steelshooter842

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Dec 14, 2018
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While I run much roomier brass and a long oal in my 260 I’m well over your load with R16 and 147’s.
Are your case marks smeared or a clean circle.
As said above a sharp ejector cutout along with possibly a slightly short case could easily make marks that look like pressure.
very clean and shiny, not a circle, more rectangular with round top and bottom. I'll post some pic tonight
 

Steelshooter842

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Dec 14, 2018
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I am assuming you are getting a round ejector plunger mark on the base of the case.
Are you getting shiny swipes? Post some close clear pictures.

It could be you have no pressure issues but the ejector hole in the bolt head has a raised sharp edge causing the mark.
 

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TxWelder35

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Are you cleaning all the case lube off the brass?
 

whatsupdoc

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That looks like excessive pressure, you need to go over everything, check your scale your loading procedure to confirm you have no issues or mistakes there.

What rifle and what velocities a you getting with your load?
 

Steelshooter842

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Dec 14, 2018
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2700 velocity. I'm loading for 2 identical rifles, one has signs the other none. 2 out of 50 with new brass had signs. Will seat deeper. now at 2.855, will try 2.84 and call it good. Don't know what else to try.
 

Steelshooter842

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Dec 14, 2018
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I got my borescope. When Insert the camera thru the chamber I see a ring around the inside of the barrel right where the rifling starts. I don't know if all rifle have this or I have a bad ring of carbon. I'll look thru my other rifle as soon as I get some time.
 

DMP

Mike
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That picture looks like a definite pressure indicator. Could those cases have been a little longer than the others?
 

Dthomas3523

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Here’s a pic of a bad carbon ring in the freebore just before the rifling.

CED69B35-C851-47D4-9B0D-CE545AFA7204.jpeg
 

Dthomas3523

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If you know for sure your were jumping and not touching lands, take firing pin and ejector out. Put a loaded round in. If the bolt doesn’t fall free, it’s likely carbon build up that is basically turning your jump into a jam.
 

Dthomas3523

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The above pic was due to negligence on my part. But with borescopes so affordable now, i use it as basically a cleaning tool. I don’t have to hope my cleaning method worked. I can visibly see the results or lack thereof.