Cooper rifle won't chamber twice fired brass

Mike Gunn

New Member
Joined
Dec 20, 2019
Messages
2
Location
Tennessee
I had this same problem recently with a 7mm rem mag two different guns a Thompson center encore and browning abolt I have RCBS fl and Redding dies called both companies and they told me that it was probably my press I have an old Herters press that belonged to my Dad from back in the 60s long story short I got a RCBS rock chucker and solved the problem
 

timotheius

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Mar 21, 2013
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58
Location
Martinsburg, WV
Just want to compliment you guys on here. I have yet to find any other forum on any subject on the entire internet that provides as much useful, problem-solving knowledge. The level of expertise of some of you guys is simply amazing, and your willingness to share is greatly appreciated. Carry on.
Agreed! Thank you all for the extensive help on this. I have ordered a small base body die. When it gets here I will try it out and see if that solves the issue. I might also tinker around with grinding a spare shellholder down to see if that makes a difference.
 

yorke-1

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Jul 5, 2008
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1,204
Location
Clearwood, WA
Oh Timotheus...where are't though...🤔.....lol.....you created this...please step back into it.....🙈🙉🙊
The right answer was given very early in the thread so he probably moved on. This is an issue with the die. A small base die will fix the issue.
 

Quintus

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Joined
Apr 15, 2013
Messages
371
Odd to me the loads on brass from the same gun get tight at all especially after 2 firings. I have a Weatherby mark V in 270Bee and another on a USRAC M70 Classic Sporter from New Haven. The fully resized cases fired in the Weatherby will fit in the Winchester, but not vice verse. I have the brass (NORMA) segregated and will get 7 to 9 loads from cases in both rifles. In theory as speculated in this thread, one or the other of these rifles brass should require a small base die after a few firings. What actually fails on these brass is the necks crack. ( should anneal regularily, but).
I too would try backing that die off just a c'hair and see if that doesn't right that ship.
 

KS2506

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Jun 21, 2015
Messages
69
Simply grind about a 1/16" of the bottom of the sizing die. That has solved the problem for me on 3 different occasions.
 
Joined
Oct 13, 2019
Messages
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Location
Raleigh, NC
I am having a problem with my Cooper rifle, .270 winchester, not being able to chamber brass that has been fired more than 2 times. I was wondering if someone could help me find a solution. It will chamber and fire factory ammo just fine. It will also chamber and fire my hand loads of brand new unfired brass just fine. It will also chamber and fire this same brass just fine when I have full length resized and reloaded it once. However, after the second firing and a second full length resizing, the brass will no longer fit properly in the chamber. It is too tight for the bolt to close without excessive force. It seems to me that even though I full length resize, the brass has nevertheless stretched out enough that it won't fit back into this chamber as normal. I have verified this by measuring all parts of the case with my calipers. Even after a full length resize, all parts of the case are still slightly larger than new, unfired brass. Can you help me understand what is going on? I have never had this problem before in any of my other rifles. I have been using both Norma and Hornady brass. Same problem with both brass. I presume that the chamber in this Cooper rifle is cut very tight? It also looks like standard full length sizing dies do not reduce the brass back to the actual size of factory ammo or unfired brass? This would be very disappointing if I can't reload brass for this gun. Has anyone seen this problem before? Also, is there a body die or something that will resize the brass back to the same size and measurements of brand new brass?
When you say full length resize, did you trim/cut the length per specifications? During the firing process, the hot gasses expand the cartridge first radially pushing the brass against the chamber walls, Then the brass is blown forward. For a lack of a better description, it is similar to kneading dough. The brass flows forward longer than the original unfired new brass even when it has been full length resized.
 

fguffey

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Mar 11, 2020
Messages
109
Location
Dallas
Simply grind about a 1/16" of the bottom of the sizing die. That has solved the problem for me on 3 different occasions.
1/16" or .0625" off the bottom of the die? I have 3 grinders, some could say 2 of them are precision grinders, one of the grinders has to be 80 years old, that would be too old to be precision. I grind angles, tapers and in-line for pilots. And then there is the grind to length side of the grinder, that is the butt cutting side. That has to make me the only reloader with three of those grinders.

It would be so easy for me to grind the bottom of dies and top of shell holders If I found it necessary. I do not find it necessary to use Reding Competition shell holders or Skip's Shims, anything that is possible with a special shell holder can be done with a feeler gage. Grinding .0625" from the bottom of a die ks equivalent to lowering the die 1/2 turn.

F. Guffey
 

KS2506

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Jun 21, 2015
Messages
69
When the die is bottomed out tight against the shell holder and the shell does not fit the chamber, then I have ground of the bottom of the die. And, it solved the not chambering problem three different times. Once with a 257 Roberts push feed M70, once with a Remington 700 30-06 and once with a Ruger 77 280. My thinking is that I was working with a minimum or tight chamber and a die that was made with the maximum limits for the cartridge specs. Any way, it worked for me. I just guessed at the 1/16". I did not measure it, it may have been a little more.
 
Last edited:

fguffey

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Mar 11, 2020
Messages
109
Location
Dallas
When the die is bottomed out tight against the shell holder and the shell does not fit the chamber,
I would have measure the length of the chamber from the datum to the bolt face. I would have measured the length of the case from the shoulder to the case head before firing and again after firing. And then I would measure the length of the case from the datum/shoulder to the case head after sizing. If other reloaders could figure out what you said they would claim you created an excessive head space condition.

F. Guffey
 

MNbogboy

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Jul 14, 2009
Messages
682
Location
Northern MN
When the die is bottomed out tight against the shell holder and the shell does not fit the chamber, then I have ground of the bottom of the die. And, it solved the not chambering problem three different times. Once with a 257 Roberts push feed M70, once with a Remington 700 30-06 and once with a Ruger 77 280. My thinking is that I was working with a minimum or tight chamber and a die that was made with the maximum limits for the cartridge specs. Any way, it worked for me. I just guessed at the 1/16". I did not measure it, it may have been a little more.
I've taken it off the shell holder a couple of times. Same line of thinking. This is for cases where chamber is short and case will not bump. Shortening to decrease rear diameter may also shorten bump to more than desirable numbers.
Small base die is a better option for "large diameter" chambers.
Shortening die or shell holder for short "tight" chambers.

Back to page two if the OP is bumping as short as new cases, it may already be too much bump.
 

Wild_Bill

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Sep 15, 2005
Messages
777
Guys please read the thread before replying.
There are so many dangerous answers.
The Op is trimming cases, he has sized and bumped the shoulders back, so shortening die or shell holder will create excessive headspace.

When setting up the die with a fireformed case just size the case so it is .002" shorter headspace measurement than fired cases. Don't go back to factory specs you might be fracturing the base of the case by overriding. We see a lot of problems where dies are jammed into shell holders crushing the cases to far and forcing the case head to expand.
Cooper rifles have tight match chambers.
Take a new case fire it then carefully size it starting with the die off the shell holder until it slowly comes to .002" shorter than fired. Then reload and fire again. If that does not work the small base die will fix the problem but don't start with the die touching the shell holder. It is very rare that shall holders or dies need shortening however sometimes it's required. The Redding comp shell holders actually reduce the amount sized then don't let you size more.
 

Rflshootr

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Joined
Jan 20, 2008
Messages
206
Location
Baltimore, MD
Listen to Wild Bill. Backing off your sizing die and setting it up on a ONCE fired case just may solve your problem. There is no need to bump a shoulder back more then .002 at that stage. Actually any more then that is just overworking the brass and shortening case life. At least try it before you go to a small base die. You have nothing to lose at that point. Make sure your case length is 2.530 to 2.540 max.
 

jdyoung

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Joined
Mar 1, 2020
Messages
111
Location
Ironman Country
Guys please read the thread before replying.
There are so many dangerous answers.
The Op is trimming cases, he has sized and bumped the shoulders back, so shortening die or shell holder will create excessive headspace.

When setting up the die with a fireformed case just size the case so it is .002" shorter headspace measurement than fired cases. Don't go back to factory specs you might be fracturing the base of the case by overriding. We see a lot of problems where dies are jammed into shell holders crushing the cases to far and forcing the case head to expand.
Cooper rifles have tight match chambers.
Take a new case fire it then carefully size it starting with the die off the shell holder until it slowly comes to .002" shorter than fired. Then reload and fire again. If that does not work the small base die will fix the problem but don't start with the die touching the shell holder. It is very rare that shall holders or dies need shortening however sometimes it's required. The Redding comp shell holders actually reduce the amount sized then don't let you size more.
Cast the Chamber. Measure the Cast according to the directions. The you know what you are dealing with !
 

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