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Stumped! Chamber pressure

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Unread 03-05-2013, 07:50 PM
Silver Member
Join Date: Feb 2012
Posts: 257
Re: Stumped! Chamber pressure

Well the problem has been identified! Got It! Coyboy/Jim had it right when he suggested it's a cam/extractor problem. Thanks Jim. My smith figured it out pretty quickly. The extractor on the Cooper is a Sako style that engages the case and then when the bolt lift's up at the top of the lift the cam engages the extractor against the rim and pulls it out a short distance to allow the bolt to come back and extract the casing. It appears the bolt has a defect so when the bolt is at the top of the cam lift the extractor is still not touching the edge for the rim, it' about .0015 short of touching the case. Looks like the hole that retains the extractor is in the wrong place or the extractor is to long. It is definitely a manufacture error with the bolt on a new rifle.

My smith is writing a note explaining the problem along with a drawing detailing the problem with measurements. I will be sending it back again to Cooper and I'm confident this time they will look at it a little more closely, verify the problem and correct it.

It's a little frustrating that I sent the rifle with a letter explaining that I thought it was a cam/extractor problem, they either disregarded the letter assuming I don't have a clue or didn't look at it very closely. They shot a couple rounds thought it, found it shot well and sent the rifle back. Now having invested several hundred dollars to prove the problem exists "by a professional that knows" I'll see how they respond.

This rifles gone from AZ to Montana to AZ to Wisconsin to AZ and then back to Montana hopefully for the last trip then back to AZ. Sure glad we can still ship our rifles, hope our President doesn't screw that up!

Thanks for all the help everyone was on this issue. I'll let everyone know how Cooper responds this time when I send it back.
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Unread 04-20-2013, 08:50 AM
Silver Member
Join Date: Feb 2012
Posts: 257
Re: Stumped! Chamber pressure

Well this is the final followup on this issue. Cooper sent the rifle back this week and I was disappointed. After all the run around the gun came back with the note on the invoice,"customer claims still an issue with stuck cases, can't find an issue, replaced extractor and bolt handle. Shot and worked fine.

No discussion with me at all and it appeared either not interested in resolving the problem or the smith handling the problem limited in ability. I've shot the rifle since and it is better, most cases come out but with a "smart quick lift" on the bolt. You have to stand up and hold the rifle so that you can jerk it loose, no way to remove a case laying on a bench. I sent several spent cases (new Lapua) with the rifle to show the problem and they sent them back with the rifle. 2 of the 7 once fired cases wouldn't eject without a very solid jerk to get them to release so if they had tried to cycle the cases I sent they would have seen it still wasn't resolved. While I had the problem identified by two smiths, one of which measured and showed data to identify the problem in a detailed explanation (at a cost of close to $600 out of my pocket), seems Cooper still didn't think there was an issue, therefore no interest in solving the problem.

Bottom line. The rifle shoots 1/2 MOA out to 600 yards. (maybe further that's as far as I've shot it so far) Probably one of my most accurate Coopers so I think I'll keep her but "VERY DISAPPOINTED IN COOPER!!!" You'd think with the price they get for their product they'd be proud enough to resolve the issue and make right. I have 9 Coopers and this is not the way the action should be. Look forward to seeing them @ the SCI convention or the Shot Show this January and let them know personally how disappointed I am
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Unread 04-20-2013, 03:05 PM
Platinum Member
Join Date: Dec 2001
Location: Long Island, New York
Posts: 2,515
Re: Stumped! Chamber pressure

Sometimes you just end up on the raw end of the deal. I've been there too.
I had a semi-custom rifle built by a well known smith who built many accurate rifles and had a good reputation on "the boards". He went out of business a few years ago in a bit of controversy.

In short - The rifle would only eject loads that were assembled on virgin brass. I was using Rem brass at the time. After the initial load, the case had to be tapped out with a cleaning rod. The smith blamed the brass and encouraged me to try other makes of 300 RUM brass. I eventually used 2 different mfg brass and had the same results. The smith insisted that it was the brass or "perhaps" the dies. I was using Redding Comp dies but bought a Foster Comp die just in case his guess was correct. It wasn't. The smith resisted my inclination to just return the rifle to him, insisting that it was something other than his work. After a year of trying everything imaginable, I gave up.

Eventually, I brought the rifle to an area riflesmith who repositioned the bolt handle to maximize the camming effect but that didn't resolve the problem either. Borescoping the barrel revealed nothing. I took a chance and asked the smith to set the barrel back and rechamber the barrel. FINALLY - the problem was completely resolved. Whatever the issue was, it was eliminated with a simple rechambering. Naturally, I had to pay for the smith's time and work to resolve a problem that was clearly the responsibility of the original smith who built the rifle. When I called him to advise what was determined and what it cost to fix his original work, I did not receive a very professional response and no offer to make good on anything. He insisted that I should not have brought it to anyone else and that any warranty that I had was now gone.

Go figure??????????
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Unread 04-21-2013, 10:09 AM
Silver Member
Join Date: Feb 2012
Posts: 257
Re: Stumped! Chamber pressure

Yea I agree but I don't think it's the fact of the deal I think it's more of a disappointment in Cooper, I've encouraged many friends into buying Coopers because I thought they were a good product. I think they're a good alternative to a custom rifle. I've lost my confidence in them. Doubt I'll buy another. Don't want to take a chance. When you spend 2K on a rifle you're afraid to take in the field because you don't want to have a problem. Something wrong with that picture!
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Unread 07-04-2013, 05:42 PM
Junior Member
Join Date: Jun 2006
Posts: 16
Re: Stumped! Chamber pressure

I've own one Cooper Phoenix and a buddy owns a Custom Classic both are in 6.5x284 and they both do the same thing. Medium/low loads on new brass and you have to yank the bolt handle to extract the brass. I found this thread, searching for a solution. Sounds like all are chambered with Coopers F'ed up reamer.
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