Can you over anneal case head??

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calgarycanada

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I did a little experiment this morning

This is hardly scientific so DO NOT do this and try to use the case afterwards.

I read a few threads about annealing and over annealing. A few posts got me thinking if it is possible to over-anneal a case head and if yes then how long does it take.

Just so we are on same page : different cases, different manufactures and even different lots will act differently so take this info with grain of salt.
I didn't wanna use a socket coz that would act as a heat sink plus I wouldn't be able to see when tempilaq melted. Also I wanted to create worst case scenario. I used 650 deg tempilaq coz I believe (just me, some people say 600)that's where brass starts to anneal. So I put case in Lee case holder and spun it with drill in the propane torch flame set to max with center blue flame just touching the case at neck shoulder junction.
First I did it with Lapua 308 case, I videoed it too. I'll try to upload but no promises as I have never uploaded video before so it may not work.
The picture is setup with tempilaq along the side & just above the case head (around the case)starting at 0.350" and finishing at 0.500" from case head(roughly). This is where I believed it's still supported by chamber but close enough to the head where if annealed I wouldn't fire that case again. I'm gonna call it "tempilaq belt"


Result: At full blast of "my" torch it took about 7 secs to melt tempilaq inside the neck(usually I'm done here) about 16 secs where case neck started glowing and 38 secs when I first noticed top of tempilaq belt staring to melt. I took 58 total secs where complete tempilaq belt was done.
I repeated the test with Winchester case, times were only couple seconds less compared to lapua.
Verdict: You guys come up with that. IMHO, this was worst case scenario where there was no socket acting as heat sink So unless you keep heating the case for another 15 seconds or so after case neck starts glowing(case is already not useable for precision work at that point) it is hard to dangerously anneal a case. Please don't quote me on that coz someone is gonna come along and prove me wrong.
Once again don't reuse such case, short cases will overheat faster and if you blow up your gun don't blame me, blame Liberals for that.
There you have it, don't over anneal cases and be safe.
Link to crappy video, if it works at all
http://youtu.be/PDKLOlbbHQI
 
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I believe the grain structure of the brass s altered at 428F so you would be best using 350F Tempilaq to indicate on the head of the cartridge. The reason for using 350 is by the time it leaves the flame it has alread spiked beyond 350F.
 
DG Photography said:
I believe the grain structure of the brass s altered at 428F so you would be best using 350F Tempilaq to indicate on the head of the cartridge. The reason for using 350 is by the time it leaves the flame it has alread spiked beyond 350F.
Click to expand...

The metal structure takes time to alter.
At 600F it takes one hour to anneal the brass. Given the heat conduction, such a long time will ruin the head too.
I bring the neck to about 750F for a few seconds to speed up the structural changes.
 
Not quite understanding the title - are you concerned that you are going to over anneal the case neck or just anneal the case head? If you are concerned about annealing the case head by accident, the recommended way to anneal that ensures that the head doesn't affect the case head is to stand all of your cases in water - typically most people I see are using baking pans filled with water.
 
I use tempilaq 750 as suggested by the dude that made my annealer, and this article from 6mmBR:

http://www.6mmbr.com/annealing.html

"The critical time and temperature at which the grain structure reforms into something suitable for case necks is 662 degrees (F) for some 15 minutes. A higher temperature, say from 750 to 800 degrees, will do the same job in a few seconds. If brass is allowed to reach temperatures higher than this (regardless of the time), it will be made irretrievably and irrevocably too soft."

-J.
 
legi0n said:
The metal structure takes time to alter.
At 600F it takes one hour to anneal the brass. Given the heat conduction, such a long time will ruin the head too.
I bring the neck to about 750F for a few seconds to speed up the structural changes.
Click to expand...

Not worried about annealing the head but altering the grain structure. Bench Source recommends 650 tempilaq instead of 750 but either will work.
 
I have ruined lots of brass when I annealed too long the first time I gave it a try. Can someone give a simple answer to how long the case should be turning in the flame? I'm lost in the argument.
 
mrdayle said:
I have ruined lots of brass when I annealed too long the first time I gave it a try. Can someone give a simple answer to how long the case should be turning in the flame? I'm lost in the argument.
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I time the annealing to about 2-3 seconds after the 750F tempilaq melts but cut it shorter if the neck starts glowing (in a dimly lit room).
I use two sacrificial cases to experiment, then I write it down.
The flame intensity is important too. I like to keep it low.
 
Watched a special on the gun network that was reviewing 556 ammo made in Turkey and followed the line from start to finish and the cases went through some sort of flame annealing machine and out the other end in an instance and the ammo was NATO certified. Only seemed o take an instant. What kind of job/quality would be this in relation to what a sport shooter would require for the experts here?----Dieseldog!
 
dieseldog said:
Watched a special on the gun network that was reviewing 556 ammo made in Turkey and followed the line from start to finish and the cases went through some sort of flame annealing machine and out the other end in an instance and the ammo was NATO certified. Only seemed o take an instant. What kind of job/quality would be this in relation to what a sport shooter would require for the experts here?----Dieseldog!
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They were probably using induction annealing.
 
legi0n said:
I time the annealing to about 2-3 seconds after the 750F tempilaq melts but cut it shorter if the neck starts glowing (in a dimly lit room).
I use two sacrificial cases to experiment, then I write it down.
The flame intensity is important too. I like to keep it low.
Click to expand...

Waiting 2-3 seconds after the 750F tempilaq melts is bad advice you will likely over anneal your necks. This does not mean your cases will fail you just may have accuracy issues.
 
mrdayle said:
I have ruined lots of brass when I annealed too long the first time I gave it a try. Can someone give a simple answer to how long the case should be turning in the flame? I'm lost in the argument.
Click to expand...

Unliss you have an accurately reproducible way of controlling time in flame, and intensity of flame, you need to set it up everytime you start out. That's not hard to do, just brush some tempilaq onto the INSIDE of the neck, and heat it up. When it goes transparent, stop.

I too have some "practice" brass that I set up on, and then let 100-200 rip. I will do a check every 50 or so to make sure it's still set right.

-J.
 
Do you folks clean the Tempilaq from inside the neck? I would think that anything inside the neck might mess with the release of the bullet.
 
dieseldog said:
Watched a special on the gun network that was reviewing 556 ammo made in Turkey and followed the line from start to finish and the cases went through some sort of flame annealing machine and out the other end in an instance and the ammo was NATO certified. Only seemed o take an instant. What kind of job/quality would be this in relation to what a sport shooter would require for the experts here?----Dieseldog!
Click to expand...

If it was flames it was probably like legion said. What part of the process was it? During the process of forming the brass there can be body annealing in different areas once formed it may under go more annealing of stress relieving process. Some ammo manufactures use flame annealing ect. while others use induction annealing.
 
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