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New Cooper 6.5x284

 
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  #1  
Old 12-23-2012, 04:00 PM
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Join Date: Aug 2011
Posts: 22
New Cooper 6.5x284

Hi
Been lurking on this sight for a long time. Finally got up the funds to buy my new Rifle. It a Cooper 6.5x284 M52 Excalibur, 24" barrel with a NightForce 5x22x56 scope with MOAR reticle. Med NightForce rings on Warne Bases. Gun with scope weighs in right at 10lbs. I Been working up a load and the best one to date is pictured. 4 shots within the size of a dime, thats a good start. I have learned a great deal from this site "Thanks You"

Virgin Lapua Brass
Fed 210 primers
51.5 gr of 4831sc Powder. I started at 48gr and worked up slowly, please do the same
140 gr Berger Hunting VLD bullet at 3.155" OAL
chronoed at 2665fps but that seem a bit slow. will verify during drop tests.

Coming from a 300RUM you gotta love the lack of recoil with this caliber. One question, will my groups get better using fire formed brass???
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New Cooper 6.5x284-cooper-reduced-244.jpg   New Cooper 6.5x284-cooper-reduced-245.jpg  

New Cooper 6.5x284-cooper-reduced-246.jpg   New Cooper 6.5x284-cooper-reduced-243.jpg  

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  #2  
Old 12-23-2012, 05:27 PM
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Join Date: Aug 2003
Location: NC, oceanfront
Posts: 3,212
Re: New Cooper 6.5x284

Beautiful gun. Was the barrel coated black from Cooper?
The load MV matches my QuickLoad results while accounting for the cold temps.
I would be surprised if it will do as well accuracy-wise with higher velocities though. The barrel is too short for that cartridge.
You'll be blastin very high muzzle pressures against the back of released bullets.
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  #3  
Old 12-23-2012, 05:52 PM
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Join Date: Aug 2011
Posts: 22
Re: New Cooper 6.5x284

Yes that is the way it came from Cooper. I want to stay accurate and dont need to get any more speed if Accuracy is going to suffer. Thanks for the confirmation on the speed. It was about 20 degrees out at 4000'.
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  #4  
Old 12-23-2012, 07:26 PM
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Join Date: Aug 2006
Location: Wyoming
Posts: 833
Re: New Cooper 6.5x284

Nvhunter I sent you a pm on some load data to try. Has been sub half moa with the hundred or so coopers I've worked with
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  #5  
Old 12-24-2012, 12:17 AM
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Join Date: May 2012
Location: Alberta
Posts: 89
Re: New Cooper 6.5x284

Great gun, my buddy has the same rifle, feels really good in my hands. Enjoy it.
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  #6  
Old 12-24-2012, 08:40 AM
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Join Date: Jan 2008
Location: Northeast
Posts: 2,253
Re: New Cooper 6.5x284

Quote:
Originally Posted by NVHunter1 View Post
Yes that is the way it came from Cooper. I want to stay accurate and dont need to get any more speed if Accuracy is going to suffer. Thanks for the confirmation on the speed. It was about 20 degrees out at 4000'.
I have been a 6.5-284 shooter for several years, my current rifles, one a Cooper 520/26", the other a Savage LRH/24". It is very likely that you can boost your velocity using 140 VLD's to 2900-3000 FPS, getting the same accuracy you have shown or better using a 24" barrel, no high pressure, no blast effects. The chonographed velocity and drop data between my two rifles is 25 FPS, the 26" Cooper the higher. Both rifles shoot .25-.5MOA 5 shot groups. I have found that fire formed brass has more influence in improving ES than absolue accuracy with Lapua or Nosler brass. Seating depth of the VLD will have a greater influence. Both my rifles are .075" off the lands. Be are to work up carefully in .5 gr increments but you should get close to 53 gr. of H4831 SC, 2920-2950 FPS. I have found that Retumbo can produce better temperature stability, and higher velocities(2950-3000FPS) with equal accuracy. I use 59 gr in both my rifles but start at 57 gr and work up in .5 gr increments.
Congratulations, you have a very capable long range rig. Don't be too cautious about wringing out it's true potential. IMHO.
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Last edited by Greyfox; 12-24-2012 at 08:46 AM. Reason: Spelling
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  #7  
Old 12-24-2012, 10:02 AM
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Location: NC, oceanfront
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Re: New Cooper 6.5x284

He could get 2950fps at 18degs with 56.8gr 4831SC. This is ~2Kpsi above SAAMI max, and with a muzzle pressure of ~12.6Kpsi(very high). At 70deg the same load will likely put him at 3030fps, 8Kpsi over SAAMI max, same muzzle pressure.
53gr 4831sc will only get him 2830fps at 70deg.

He won't even get close to 4831 velocities using Retumbo.
The highest there is ~2800fps with a case full(including a full fireformed case).
His pressure would be 15Kpsi below SAAMI max, and likely producing very high ES.

The best he can do velocity-wise in 24", and possibly overall, is 60.5gr Ramshot Magnum at 70deg. This is barely SAAMI max, ~3016fps, not compressed, but muzzle pressure is still high at 13.4Kpsi.
With this load same conditions and a 28" barrel, he'd have 3130fps, same pressure but muzzle pressure would be down to where it is right now (~11Kpsi).
This is what a 6.5x284 cartridge is for.

No matter what, his muzzle pressures are high with a 24" barrel & this amplifies any flaw in release of boat tail bullets. It may not show up at 100yds, but it's a factor in distant shooting. The slightest crown flaw will show up big time, and ES is raised also.

It never made any sense to run big cartridges with short barrels..
With a 28" barrel, my 6.5WSSM can run circles around a 6.5x284 in 24". But a 6.5x284 in 30" would leave me in the dust(as you would expect from a way bigger case).

His gun, with that barrel length, would be perfect in 6.5x47L.
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