Annealing Myths vs Science

[stevenc23]

Posted this over on the Hide as well. Would love to hear others thoughts on annealing.

Kind of long winded but bare with me. I am relatively new to long range precision shooting and have definitely been bitten by the bug. Started with factory ammunition and now have taken up reloading. Annealing was the next step in my progression. As is my nature I read everything I could and picked the brains of accomplished shooters and reloaders.

Like most topics it isn’t always easy to separate fact from fiction. And with annealing I found lots of opinion based on personal experiences but very little science. With my science background and a degree in Chemistry I knew much of what was being said simply was not true.

For those interested in some light reading here are a few good articles and discussions to read to come to you own conclusions

https://vacaero.com/information-reso...dge-brass.html

https://web.archive.org/web/20160131...ssertation.pdf

http://forum.accurateshooter.com/thr...brass.3868113/

https://www.youtube.com/watch?v=J4cmxWaMpOw

FWIW these are the conclusions I have come to based on scientific evidence.

1)The biggest myth is that you can easily over anneal cartridge brass. As per the above studies, you can heat brass to 1300 degrees F for an hour and you will NOT ruin the brass. Directly from George Vander Voort, an expert in the field of Metallurgy “"It recrystallizes the grain structure, removes the cold deformation and returns it to the initial annealed condition with full ductility.”" So if one hour at 1300 degrees F does not damage cartridge brass I think it would be pretty difficult to “over anneal” brass in a few seconds. Caveat –- you obviously to not want to anneal the case head or close to the head.

2)You do not burn the zinc out of the brass when it turns red.

3)You can anneal cases many (many) times, without harming them.

4)By properly annealing (and repeated annealing), cases life will be increased (unless overloaded).

5)Like most aspects of reloading consistency is the key. It is easy to anneal brass but more difficult to get all brass annealed to the same grain structure/hardness

6)Water does nothing for the process

Just my opinion based on my research.

[XC700116]

I've long thought the same things but lacked the motivation to research it to this level. Heck look at a fresh box of Lapua Brass, you can't tell me they are stopping the micro second that it hits 750 degrees, because you won't get near that color from any brass from that temp/time combination. If you keep it in the right area on the case it's not a problem.

As to the consistency, I don't think anything out there is as consistent as induction annealing.

[Hoser]

I have been annealing for many years but didn't take it serious until the last few years.

As with anything, consistency is key. Induction annealers might be stupid expensive but they yield XXX brass hardness today on XXX setting, and will do it again three weeks from now and again in two months, ect.

[gta_spec]

I had not thought about case annealing until now, but I have several 5 & 10kw induction heating systems on hand. Maybe I should get a case feeder and see how it works.

[Blowby]

I had not thought about case annealing until now, but I have several 5 & 10kw induction heating systems on hand. Maybe I should get a case feeder and see how it works.

When it's finished I'll buy one from you. Annealing suck the old fashion way.

[feal]

can you clarify comment 6 regarding water? im not sure of the context but if you are using water to quench, im pretty sure that you would get different properties than air cooling. i guess it would depend on specific composition as well

[gta_spec]

I believe that only ferrous materials are affected by different quench rates. Everything else only cares about the temperature that it is elevated to, not how quick it's quenched.

[feal]

Cooling rates will affect grain growth which should affect properties. Quenching usually freezes a phase before it can transform to another. I'm pretty sure it's for more than just ferrous materials.

[feal]

i don't know where some of the myths are coming from, but control of the cooling rate can be very sensitive as well as what temperature you are dwelling at depending on what temperature the different phases form at. This is ( see chart) also dependent on the composition of the brass.

[Delfuego]

I would defer to the knowledge of benchrest shooters. They reload better than anyone on planet earth. They don't bother to quench. None of the machines they build use quenching. Even if there is even a minor effect, why bother. It is just rifle brass, not a samurai sword, lets not get carried away with metallurgy or get sidetracked by minutia. If I had an annealer I would do it every reloading. Since I don't, I make a trip to a buddy's shop every 3rd or 4th firing. The purpose is consistent neck tension and brass life not molecular whatever. Even if I had absolutely perfect brass, my reloading and shooting skills are still 1/2 moa. Hell my Chargemaster is only accurate to .1 +/- grain of powder...