Cold bore high pressure

2rjshort

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May 5, 2020
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46
Location
Virginia
I have a rifle that exhibits high pressure from the very first shot cold bore. I will get a hard lift on the bolt handle and ejector marks on the brass. After the first shot the rifle fires like normal with no signs of pressure what so ever. Has anyone ever experienced this?
 

2rjshort

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May 5, 2020
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Virginia
For the most part yes. However this morning I decided chronograph 5 rounds on a dirty barrel. The first load had the bolt stick and light ejector mark. I waited 10 min between shots and the didn't have an issue with the following 4.
 

jebel

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Jun 15, 2018
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Oregon
Do you leave oil, or could there be cleaning solvent, in your chamber during storage that was not cleaned out before beginning to shoot? A slick/lubricated chamber can cause increased pressure against the bolt, as the case is unable to grip the sidewalls of the chamber (the lubricant in the chamber also reduces available volume, which can increase pressure).
 

Bang4theBuck

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Nov 19, 2013
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Those were my thoughts as well, hence my previous question. Was thinking maybe he should wipe the cheer with brake cleaner or similar before shooting next time.

I think that the bolt thrust scenario goes unnoticed by many.
 

2rjshort

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May 5, 2020
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Virginia
I generally don’t use oil since I shoot so often but I do keep running patches until the bore is dry. I use a bore guide to help keep solvent out of the chamber but now I’m wondering if it could be running back past the guide into the chamber
 

Bob Wright

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Jan 23, 2018
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Litchfield Park, Az.
If it happens everytime, it is odd. Try it next time with a cold and clean barrel. Clean chamber well. Use a dry clean bore mop there.
If it still does it, maybe look at brass head space, bullet jump and check for other pressure signs. Swipe all fired/deprimed brass over very fine (1000 grit) sand paper, one time and see if ejector marks can be discovered. You may be at your max and summer temps are pushing you to the dark side...
 

dok7mm

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Apr 13, 2015
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west texas
The o-rings may be worn out, but most likely the solvent is running off your patch and down the outside bottom of your bore guide. It can play havoc with your trigger and also foul your chamber, causing just what you encountered.

Each of my bore guides has a small cotton rag tied around the mouth of the guide and stops that leakage. I still dry my chamber, just in case.
 

26Reload

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Dec 25, 2016
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SE Idaho
I have an el-cheapo bore guide....but always finish cleaning by running a cleanup pad into the lug area and the chamber....
Then of course check it all out with my
SUPERDUPERCHRONICSUFFERAGEBORESCOPE....
 

djfergus

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Dec 25, 2015
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1,656
Have you tried not cleaning the bore at all after a range session, then trying a cold bore shot at the next range session & do you still show pressure. What powder are you using?
 

djfergus

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Dec 25, 2015
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1,656
What is the cartridge & is it a factory barrel? Barrel with a barrel nut?
 

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