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Old April 10, 2013, 12:17 PM   #1
rebs
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case neck tension ?

After reloading 223 cases 5 to 7 times does the case neck tension change ? I have noticed that some cases are easier to seat the bullet in and wonder if it is because of a change in case neck tension. Also accuracy has dropped off with these cases, groups have opened up some. Is this the point where these cases need to be annealed ?
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Old April 10, 2013, 01:07 PM   #2
mikld
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I would think it wouldn't change if the cases are sized each time. But, theoretically, the neck brass may thin out (stretch) after several resizings/trimmings...
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Old April 10, 2013, 01:14 PM   #3
William T. Watts
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My thoughts is after several firings and sizings the necks have become hardened and more resistant to the bullets being seated. I would think annealing would help, I personally haven't had any luck annealing brass but some fellow swear by the process. I usually do not try for more than 3-4 firings before pitching them in the recycle bin.. William
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Old April 10, 2013, 01:38 PM   #4
eldermike
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Springback changes when hardness changes.
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Old April 10, 2013, 01:45 PM   #5
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I'm thinking that the groups opened up due to inconsistent neck tension on the various cases. Probably chunk the cases or anneal them, but I'm not an annealing pro, so advice on that needs to come from others.
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Old April 10, 2013, 01:52 PM   #6
Brian Pfleuger
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Yes, it's a hardness issue.

Annealing would help but can be dangerous if over done.

You must anneal the neck, shoulder and perhaps 1/4" down the body but no further.

Even without annealing, most rifle cases that have been properly resized should last a dozen or more reloads.

My opinion of annealing has changed a bit over time. I first concluded that a novice could not safely do it without fairly extensive equipment or trouble. I have since concluded that it's not as complicated as I tried to make it.

Heat doesn't do anything at all to brass until it gets to (IIRC) 495F. At 495, it takes quite a while to anneal. The rate of annealing is somewhat exponential though, small increase in temperature decrease the annealing time dramatically.

I've settled on a "time honored" method. Well, it might not be honored but it's been done for years.

I hold the case about 1/2" below the shoulder and hold the shoulder in the "inner" flame of a propane torch. I rotate the case in the flame until it's too hot to hold and then drop it into a bowl of water.

Imprecise but effective, for me.

I can feel the difference when I size the necks.
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Old April 10, 2013, 02:07 PM   #7
F. Guffey
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Neck tension, I can not measure neck tension, I can measure bullet hold, I am the fan of bullet hold, I want all the bullet hold I can get, there is no such thing as too much bullet hold, there is no such thing as too much crimp.
Back to tension, I understand interference fit, I understand crush fit, but neck tension?

If firing a 6 time fired case is the same as firing a new case, who wants new cases? If sizing a 6 time fired cases is the same as sizing a one time fired case who wants to pay the extra money for new cases?

And again, the part that makes no sense, fire to form, then necks size after the next 5 firings ‘THEN!! start over by full length sizing the case to minimum length, again, and again I ask, How is that possible? The case has been fired 6 times and that is the reason neck tension does not make sense to me. My cases increase in resistance to being restored back to minimum length/full length sized.

But, there are reloaders that fire cases 45 times, after firing 45 times the cases handle like a doll buggy, the cases do not travel, the brass does not flow, the cases do not require trimming etc., and they do not weight the case before the start at the #1 firing and after firing the case 45 times they still do not know the weight, If I put that much effort is a case I am going to save a case from the same lot for comparison.

Again, I was at the Dallas Market Hall gun show when a proud owner if a rifle built by a friend accused him of building a rifle with head space problems, and I said nothing. It was recommended the proud owner bring the rifle in to be checked, THEN! the proud owner walked down the isle and I ask, “would you allow me to examine the case?”. After examining the case I ask if that was the only case he had and was he reloading/firing it over and over and over etc.. The man that built the rifle ask to see the case again, he then realized the case would just support itself when stood on the table.

Then came time for a second unbiased opinion from the man of few words, the proud owner agreed. He was sent half way across the building, with the instructions he was not to say anything about who built the rifle or what I said about having one case, to have the case checked out, the second opinion smith took the case apart and measured the case body thickness, .0025 thick, he then asked the owner if that was the only case he had and was he reloading and firing it over and over and over etc.. The proud owner was not happy, he was proud of that case and in his effort he stepped into it, he never showed up to have the rifle checked out. I did offer to form 200 cases for him for free but by that time he was still complaining about the case being ripped apart. In closing he did say he was told .0025 was a good thickness for paper, but by the time a case gets that thin it is time to start over on ‘A NEW CASE’.

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Old April 10, 2013, 02:20 PM   #8
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Thank you for the replies, I guess its time to retire these cases and move on to some more once fired ones.
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Old April 10, 2013, 02:44 PM   #9
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I usually load high pressure, so primer pockets get me long before I start having neck problems. Brass does eventually need annealing, but 5 to 7 is a bit early for that if your brass was high quality brass. If you are using questionable brass, anything is possible. I have never had any problems with necks not holding tension. I have had plenty of split necks, but not necks that would not hold tension.
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Old April 10, 2013, 04:07 PM   #10
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Wasn't that long ago that I was getting into a rather high reload count on some good Nosler brass (all from the same lot) and I could feel variances in neck tension when I seated bullets. They all had sufficient tension to hold the bullets, but that tension was not equal from case to case. I shot them that one last time and discarded that brass.
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Old April 10, 2013, 05:38 PM   #11
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A friend of mine reloaded the same .308 Win. Federal brass case 57 times full length sizing it every time. All bullets shot into about 3/8ths inch at 100 yards. Maximum load used; 42 grains of IMR4895 under Sierra 168's and Fed. 210 primers. No loosening of the primer pocket whatsoever. Case was never annealed. Chamber was a standard SAAMI spec one; no tight neck.

Case neck tension in the ammo industry is typically referred to as the bullet's release force needed to push (or pull, if measured) it out of the case. It needs to be uniform to about a 10% spread for best accuracy. Too much will increase pressure quite a bit as well as degrade accuracy; if it's too much, the case head may rupture when fired. MIL SPEC 22 and 30 caliber rifle ammo has 40 to 80 pounds of release force. Commercial ammo is somewhat less. Most reloaded rifle ammo has a release force for its bullets between 5 and 30 pounds.

Having seen the results of firing a round whose case neck had hard-bonded to the bullet (disimilar metal stuff) and the neck shot off with the bullet, the primer readily fell out of the case when it was ejected. Its shooter commented that the rifle had a lot more recoil as well as an extra loud report. That ammo had been reloaded some 20 years earlier. So, there is a limit to what neck tension or release force can be as far as safety is concerned.
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Old April 10, 2013, 07:31 PM   #12
jepp2
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Quote:
Imprecise but effective, for me.
Case necks do harden with firings. It is due to the neck being undersized by the die, then expanded by the neck expander when the decapping rod opens the neck back up.

I notice it when I size with a Lee collet die. When the necks get hardened enough they will not properly size due to the pressing of the collets.

If you do decide to anneal your necks, you can find a better method described here.

As mentioned, annealing is a time/temperature relationship. The key is obtaining the correct temperature quickly enough to limit the affected area to the case neck/shoulder portion of the case. Using the 650 degree (F) Temp Stik, controls your heat input and avoids overheating the neck. Quickly cooling limits the affected area to the proper portion of the case.

Neck splits are just an indication of the neck brass getting hard and in need of annealing.
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Old April 11, 2013, 10:53 AM   #13
F. Guffey
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#11
Bart B.
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Posts: 1,892 A friend of mine reloaded the same .308 Win. Federal brass case 57 times full length sizing it every time. All bullets shot into about 3/8ths inch at 100 yards. Maximum load used; 42 grains of IMR4895 under Sierra 168's and Fed. 210 primers. No loosening of the primer pocket whatsoever. Case was never annealed. Chamber was a standard SAAMI spec one; no tight neck.



I had a friend tell me the same story, I replied with “FANTASTIC”, I was at the Market Hall Gun Show in Dallas, TX. same thing, a proud owner approached a builder of very fine rifles with a claim the rifle he purchases had a head space problem, I said nothing. After they decided on a plan the proud owner moved down the isle and I asked to see his case with all the problems, he was more than happy to oblige. I asked him if that was the only case he had and I asked him if he was reloading it over and over and over etc., I offered to form 200 cases for his chamber so he could spread the abuse over a greater number of cases, then about that time the builder of the rifle asked to see the case again. Then they decided they needed a third nonbiased opinion, he was sent off to have the case checked by a third part with the instructions no mention would be made of my opinion and he was not to know who built the rifle. After a short period of time he returned, upset, seems the third party pulled the case apart and measured the thickness of the case body, .0025, at that point the third party informed him .0025 is a good thickness for paper but did not work for cases. The third party then asked him if that was the only case he had, the third party wanted to know if he was loading that one case over and over and over etc.. he aslo suggested the case could not be sized without pulling apart when the ram was lowered etc..

We decided he must have been one of those bench resters. The proud owner never returned to have the rifle checked. He was proud of that case, he was not happy when the third party pulled it apart.

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Last edited by F. Guffey; April 11, 2013 at 10:55 AM. Reason: remove an a
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Old April 11, 2013, 11:07 AM   #14
Brian Pfleuger
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Quote:
Originally Posted by jepp2
Case necks do harden with firings. It is due to the neck being undersized by the die, then expanded by the neck expander when the decapping rod opens the neck back up.

I notice it when I size with a Lee collet die. When the necks get hardened enough they will not properly size due to the pressing of the collets.

If you do decide to anneal your necks, you can find a better method described here.

As mentioned, annealing is a time/temperature relationship. The key is obtaining the correct temperature quickly enough to limit the affected area to the case neck/shoulder portion of the case. Using the 650 degree (F) Temp Stik, controls your heat input and avoids overheating the neck. Quickly cooling limits the affected area to the proper portion of the case.

Neck splits are just an indication of the neck brass getting hard and in need of annealing.
Yep, I only size with Lee collet dies. I've researched the various annealing ideas extensively, including the one in your link. My fingers work fine. If I can still hold the case, there's no way anything below that point is REMOTELY close to hot enough to cause problems. I get the same color changes described in your link. They look like factory new Lapua cases. The distance that the anneal line goes down the body is pretty consistent. Consistent enough for me, anyway.
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Old April 11, 2013, 01:10 PM   #15
F. Guffey
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Originally Posted by jepp2
Case necks do harden with firings. It is due to the neck being undersized by the die, then expanded by the neck expander when the decapping rod opens the neck back up.


jepp2, then there is firing, nothing is more violent when it comes to expanding/working the neck than firing, when I have control I want to limit neck expansion when firing.

I have been told about necks being worked and splitting etc.. It is nothing for me to take suspect cases and neck them up, going from 30/06 to 35 Whelen is a work out, going from 280 Remington to 338/06 is also a work out.
Then there is the total workout, I have no reservation about testing cases, I have inverted forming dies in a press to test cases, everyone knows the case can not go through the die from the small end, I test the case by crushing the case between the shell holder and die, good cases will form into a bellows and or an accordion, in appetence. Crushing work hardened cases is a work out, getting them to start is difficult and can cause the case to rip and or split.

I anneal cases, I make tools for annealing, from the beginning there have been simple rules to follow, in the big inning there were those that used a candle, one of them held the case in his hand while annealing with a candle, he became one of those that quit speaking to me because his methods and the simple rules could not be followed. Then there is the fellow that has the video, he holds the case in his hands, and ???? then suddenly and without warning the video stops and restarts, with his hand no where is sight, one simple rule, heat travels, heat travels to cold.

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