Cooper rifle won't chamber twice fired brass

[fguffey]

I think you may be bumping the shoulder too much causing a bulge at the base of the case.

It is impossible to move the shoulder back in a die that has full case body support. It is easier for the case to travel up the die than down. The case would stick in the die before the reloader could upset the case head. The only way a reloader could crush a case and or move the shoulder back would be to size a case in a die with a flat shoulder.

F. Guffey

 

[358 Guy]

I highly doubt that your chamber is too tight as you have stayed it will chamber factory and once fired brass. Typically neck sized brass starts to get tight at around 3 to 4 shots. I think you have a minimum spec chamber. Still within spec and nothing wrong with it. I used to build all my rifles with a minimum spec chamber till I got tired of cutting the bottom off of factory dies. Some dies just won't push the shoulder back even when bottomed out. If you haven't measured your shoulder setback you don't know if you are sizing you brass enough at the shoulder length. You need to measure a fired round and then compare it to your sized round. If you are not setting the shoulder back .001 to .003 then you are basically neck sizing. If your die isn't sizing far enough and your all the way down then you have 2 options. Have a machine shop take .010 off bottom of your sizing die or take your shell holder and put it upside down on a piece of sand paper and remove some off the top till you get the setback you need. Redding makes compatition shell holders that have differing heights maybe one of those will give you the extra crush you need.
Most brass will go 5 shots or so before needing trimmed so I doubt that the necks are too long but it's an easy measurement so check it. Cooper's are pretty much a semi custom gun so I wouldn't doubt that you have a perfect minimum chamber on yours.
Get those measurements and get back to us and we can better help you.
Shep

I had a similar problem with a minimum spec. 284 Win. barrel. I did some experimenting using a feeler gauge inserted between the base of the cartridge and the shell holder to push the cartridge a bit further into the die. I started with a .002 gauge and increased in .002 increments until the cartridge would chamber. ( this occurred at .006 ) I had marked the shoulder area of the case prior to doing this with a Magic Marker to verify that I was hitting the shoulder. I then chucked the shell holder in my lath and cut .008 off of the top of the shell holder. That solved the problem for me. Another option is to send the sizing die back to the manufacture along with one of the fired cartridges that would not chamber and see what they have to say. Redding has modified dies for me in the past. Good luck!

 

[David Urasky]

Here's a new look at the problem. I was working up dasher loads and was really pushing them as I'm shooting a bolt action pistol. As I got to max load for that chamber I found the same problem you are having. Except it was just one hot load. No heavy bolt lift, slight primer crater no excessive primer flattening. My problem was the brass expanding in the head below where the die reached. I'm using both Whidden and Wilson dies so they are not the problem.

I normally shoot Lapua brass and have never had this problem. If I use fire formed Lapua brass at the same loads the is no problem. The problem only exists while using Norma brass. Although I no longer have a Rockwell hardness tester at my disposal I'll bet that the Norma brass has a softer or thinner head than the Lapua. To test the fit I chambered a piece of shot out barrel so the headspace gauge sits flush with the bottom the the barrel and drop the sized brass into it. If it drops in completely I'm good. If it doesn't I know that load is too hot for that brass.

Just my experience. Reduce your loads and try it again.

 

[nocannons]

View attachment 184466

Couple things I noticed on this case. It did not even make it into chamber far enough to scratch shoulder or neck so definitely not an issue with shoulder bump. I have only used sb die on 223 to make sure they worked when using range pickups. seemed strange to me that when you showed brass later in post rub point was apparently on opposite side of case. I am no gunsmith it looks to me like problem could be bad case alignment in die ( neck to body not aligned properly) if that is even possible. The more i think about it i am leaning toward the different size shelholders or return die with fired cases. Might take a new case and run it through die coat it with sharpie and see how it looks or a once fired case.

 

[Mike Matteson]

If we are looking at loads being to hot. What does the primers look like after being fired? Overall case length being to lo long can cause higher chamber pressure. Neck thickness can create higher chamber pressures also. Some chambers are set up for tighter dia. Requiring the necks to be cut to create proper fit and room to expand. Resizing the case the neck wouldn't show up as the problem I believe. I didn't see if the necks were being cut for thickness.
SSS
Mike

 

[jdyoung]

Well if you have identified the right spot for the bind, and it is the only spot then I would say Cooper needs to fix the gun. If a .468 brass won't fit in the gun the chamber is cut smaller than Saami minimum spec by over .0028. Either that or you are going to need a small base or custom die to load for this gun.

Why not do a cast of the rifle chamber with Cerrosafe? Not that hard to do. Give you a basis for your talk with Cooper . Follow the directions . Take measurements ONLY after the Cerrosafe cast has cooled for 1 hr.

 

[sailorjim]

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?

Try a small base F/L sizing die for use in auto loaders.

 

[Huntz]

I did not read all the replies,but a small base die will solve your problem.

 

[Tim Sharp]

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?

 

[Rebellare]

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.

 

[amadjuster]

For what it's worth, Cooper does the target test with reloads. I haven't seen what his reloads were but I am wondering if maybe he is loading maximum loads and is suffering the start of case separation. Someone asked him to do a test with a paper clip to see if there was a ring in that area but there was never an answer.

 

[fguffey]

I measured the web area of some Winchester cases. New 4.635", Fireformed in Steyr: 4.675, resized 4.666. It's a cheap and easy fix to switch dies...not to mention Hornady currently has a rebate. Obviously the small base dies will work, too.

If reloaders understood what you just typed some would get dizzy and others would pass out. Let us say I purchased a new, over the counter factory loaded box of ammo for testing in a 30/06 chamber. the first thing I would do would be to measure the case head diameter; and then? I would record the reading. Next I would head for the rang to fire my factory loaded ammo. After firing I would measure the diameter of the case head and compare the two readings, that would be before firing and again after firing. I would expect the case head expand .00025" during the first firing. You claim the case head expanded .040", that would indicate a case head expansion 160 times greater than recommended. How could that happen? Very soft case heads.

I do not believe you you understand how difficult it would be to size a case head down from .675" to .666".

small base dies will work, too.

I have small base dies, it is not easy to measure a small base die. And then I have real small base dies. My very small base dies will keep 10 our of every 10 cases. I have two of them, I guess I should get my money back but there are those that do not believe they exist. If I could get one to work I could reduce the diameter of the case head .005".

F. Guffey

 

[mdvctry]

Reading through all the post and it was mentioned several times to check the sizing die setup. But, I think, only one person actually gave a suggestion in what to do to change the setup for the sizing die; the shooter mentioned to back the die off a bit until cases fit inside. This is most often the problem. and to check how a case fits as compared to SAAMI specs at the body, shoulder and if it's too long and needs trimmed, a really good way to see this is to use a.... ready for it? A case gauge. Then you can see and compare cases that are correct to cases that are not so much...

270 WIN Ammunition Gauge

Choose between SLOTTED or NON-SLOTTED. AMMUNITION GAUGES are uniquely designed to check loaded ammunition, giving you the ability to check your factory ammunition or reloads against a spec chamber. The gauge is machined to the SAAMI minimum chamber spec for the 270 WIN caliber. This…

sheridanengineering.com

 

[fguffey]

a really good way to see this is to use a.... ready for it? A case gauge. Then you can see and compare cases that are correct to cases that are not so much...

It works because it is a datum based tool; reloaders that do not understand what a datum base tool is use the Wilson case gage as a plop tool. They simply plop a case into the gage and use their thumb nail.

F. Guffey