Annealing?


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45Badger
February 8, 2003, 11:13 PM
I'm new to rifle reloading (50 successful rounds- bullets punched paper, action cycled, and I still have all fingers!), and have seen a few references to annealing.

What is it? When is it necessary? Is it necessary?

If it matters, I am reloading .308 for my M1A.

Thanks!

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HSMITH
February 8, 2003, 11:38 PM
Annealing softens the brass to keep it from splitting, makes it easier to size and neck tension more consistant. For what 308 brass costs just shoot it 4 or 5 times and heave it. Unless you have a match M1A the chamber is going to be loose and hard on brass anyway. In your case I really don't see annealing as beneficial.

Edward429451
February 8, 2003, 11:59 PM
I just picked up a batch of LC 75, once fired Military brass at the gunshow recently and it shows the coloration in neck area indicitive of already having been annealed. Does the military anneal their new brass?

Obviously yes but I didnt think the military reloaded cartridges, so why the annealing?

mete
February 9, 2003, 12:41 AM
The british in India found that the case necks would split in storage .This is the process called stress corrosion cracking. It is due to things like moisture and ammonia ( created during thunderstorms) in the air. So the problem has been known for many years and the solution is to anneal the necks.

BigG
February 9, 2003, 04:57 AM
The discoloration on the necks of military brass would also be present on factory ammo, IIRC, but they polish it off on factory for cosmetics.

Edward429451
February 9, 2003, 08:39 AM
Learn something new every day. Thanks.:)

Ryder
February 10, 2003, 04:49 AM
I've taken metallurgy and heat treating classes but there's something I don't understand about this brass case annealing process as it is being performed by handloaders.

Ever since the first time I read about this in a manual I still can't understand why it is recommended to tip them over into water after heating.

I've always considered quenching to be a hardening process. If you wan't large grain structure to soften a metal you cool it slowly.

No? What am missing here?

PaulS
February 10, 2003, 07:35 PM
Ryder,
Iron and it's alloys harden with quenching while copper and it's alloys soften with quenching. The critical part with anealing cartridge brass is not to overheat it in the process because the heat will cause the zinc to precipitate out and change the grain structure in the metal.

PaulS

mete
February 10, 2003, 08:08 PM
Here are the metallurgical facts - you only want to anneal the necks not the body and you don't want to overheat the necks so you put it in water heat the neck and tip it over. Cartridge brass ( 70% CU, 30% ZN ) can be hardened only by working not by heating and quenching like steel. Zinc does not precipitate in brass . It is the heating that anneals brass and it has nothing to do with whether you cool it quickly or slowly.I've heard this myth about quenching brass but try it yourself - take two pieces of brass that are hardened , heat , cool one quickly and cool one slowly - they both come out soft.

braindead0
February 11, 2003, 12:11 PM
Well, if we're going to talk facts...

70/30 Cu/Zn needs to be held at 500F for 1hour to fully anneal.

And yes, quenching copper and copper based alloys in most cases has no affect except to speed cooling. Which might be beneficial.

45Badger
February 11, 2003, 09:11 PM
So, if I want to anneal cases, how do I do it? Bake for an hour at 500 degrees and then dunk in water?

jacks308
February 11, 2003, 09:45 PM
ouch:banghead: I'll stay away from that one when it goes :what:

Jack:D

BigG
February 11, 2003, 09:46 PM
You prolly won't have to do it with 308. It's usually those wildcats that they want to preserve the brass forever. Brass work hardens when you keep expanding and resizing it is the thing. Just chuck your 308 brass after you've loaded it 6-8 times. It's cheap.

The way I've seen it done is put in a flat pan base down fill with water to just below neck. Apply blowtorch to necks, and tip em over. That's the layman's way. Don't know how a pro would do it.

Note: Only the neck should be affected. If you heat the base or body you might have case failure. Caution!

Art Eatman
February 11, 2003, 10:35 PM
If you heat in the pan of water, go slowly. Move the flame around. Heat to a very dull red, at most. Just barely visible...

This is very rarely needed if you just resize the case necks. And, it's not really worth bothering with for such as the .308; brass is too cheap to be worth the hassle.

Art

bogie
February 12, 2003, 10:56 AM
DO NOT PUT THE CASES IN AN OVEN!

If you anneal the case head (the part where the primer goes), you will very likely have the cartridge blow up on you - That part of the case is supposed to be hard.

mete
February 12, 2003, 10:58 AM
45Badger, if you annealed your cases in your kitchen oven at 500F you would anneal the whole case thats DANGEROUS. Since annealig is a time and temperature dependent process higher temperaturs would require shorter time . The recommende d way with a torch and the case in water is fine . And by the way the factories do it with a torch too.

Ryder
February 15, 2003, 05:01 AM
That explains it. Thanks for the reply guys!

DonQatU
February 15, 2003, 01:43 PM
First off, .308 Win cases are cheap enough that it doesn't pay to anneal them.

If you reload rare, very expensive or wildcat cases, then annealing may be called for.

I anneal my .223 cases when forming 7mm TCU. Especially when using hard military brass.

I use an electric cordless drill, the case holder from a Lee trimmer, a 650F Tempilstik, a Bernz-O-Matic torch and a bucket of cold water.

You'll have to experiment a little on where you mark the cases with the Tempstik. I mark the .223 cases that I form 7mm TCU right at the mid portion of the shoulder.

I adjust the flame and turn the drill on at fairly low RPM aiming the flame at the center of the neck.

When the Tempstik melts, I immediately quench the case (while still held in the drill) in the cold water. This stops the annealing process.

Don

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