Cooper rifle won't chamber twice fired brass

timotheius said:

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?

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timotheius said:

I tried trimming the brass, and that did not solve the problem. As to the other questions: it is not a shoulder bump issue. I use a sinclair bump gauge and measure carefully to make sure I am getting the correct amount of shoulder bump. I have used both a redding FL bushing die, and a Lee FL sizing die. I used the redding die to fine tune the shoulder bump. I used the Lee die, contacting the shell holder with cam over, to try giving it a lot of shoulder bump. Neither made a difference. The black marker trick sounds like a good idea, I will try that next.

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timotheius said:

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?

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26Reload said:

I would take a black marker and coat the entire piece of brass...let it dry....then slowly push it in with the bolt...feeling when resistance starts...slide it back out and look over the scuff marks on the brass....should tell you exactly what going on....

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LaHunter said:

My opinion (and I am no expert) is this:
1) do you have your die set up so that you are making solid (not excessive) contact with your shell holder to the die so that you get some cam over at the top of your up stroke? If not, you should be to get the full effect of FL sizing.
2) It usually take a few firing for the brass to 'grow' to the full dimensions of your chamber, it appears that it takes 2 firings for your rifle. If you are getting full contact with your shell holder/die on the top of the ram travel and getting cam over, and still not sizing your brass enough, you may need to look at getting a shell holder with a shorter rim or another die, which will allow more sizing. Or you may want to get your chamber checked out by a gunsmith to verify the sizing is within SAAMI specs
3) Are you trimming your necks? As you size your brass, the lengths grows, so your brass over all length could be too long and the necks could be bumping into the end of your chamber. Assuming you are FL sizing properly, this may be the most likely scenario.
4) I would recommend getting a Hornaday LnL comparator (or something similar) so that you can measure your new vs fired brass to know for certain the amount of shoulder push back you are getting. This is a valuable tool for precision reloading. You mentioned that you have measured your brass, how did you go about this and what did you see?

hope this helps.

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Dean2 said:

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.

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