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Old March 30, 2011, 03:06 PM   #1
b money
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How did I do?

Ok I wanted to give annealing a shot as I have a few 243 range pickup cases that I wanted to neck up to 308 and a ton of old 30-06 cases that could probably be annealed before sizing. So I took a few 243 cases and held them with my fingers and proceeded to anneal them(trying to rotate them evenly) until they were too hot to hold then I dropped them in a bucket of water. looking them over I can see a very slight color change from the neck to the bottom of the shoulder(uneven in spots) I just want to make sure I did ok before I go any further, as I don't want the case head to split when I fire them. but it didn't get too hot I don't think because I was holding them. any input, comments, or thoughts would be great.
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Old March 31, 2011, 09:40 AM   #2
TATER
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Join Date: November 19, 2002
Location: Mississippi
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Turn the lights off

If you are simply judging by too hot to hold then no, that’s not telling you anything.
If you hold the flame too far away it will get too hot to hold before it reaches the
proper temp.
Turn your lights off...You are looking for a faint glow at the neck and shoulder just
before its too hot to hold. A bright glow is too far.
It will take some practice learning what the flame should
look like in relation to the brass. But, its not hard.

On the back porch at night works best for me.
HTH
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Old March 31, 2011, 02:43 PM   #3
Unclenick
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I've recently read a couple of things on this topic, and the metallurgists seem to think even dull red in low light (usually given as about 1100°F, give or take, depending on your eyesight and how dark it really is) is still too warm for good tensile strength of the brass. They point out that the excessive grain growth and accompanying loss of tensile strength, ironically, leave the necks more prone to splitting than lower temperature stress relieving does, splitting in as few three to five reloads.

You hear the standard recommendation to "re-anneal" every four reloads or so, and I've repeated that myself, as it seemed be a general consensus. But I've had new rifle cases that lasted four or five times that without stress relief if I was neck sizing and the loads weren't too hot. I've had low pressure target loads in .45-ACP go 50 reloads doing no stress relief. So, with the new reading under my belt, I'm inclined to believe doing it every four times is a necessity only because people are overheating it (though it may still be desirable for maximum consistency of neck tension).

What complicates matters is that stress relief happens faster as temperature goes up. If you were able to hold the neck and shoulder at about 570°F for an hour, you'd relieve stress with minimum grain growth and maximum retained tensile strength (for stress-relieved brass) and good bullet grip and start pressure. Unfortunately, the head of a case depends on the work hardening stress it received at forming to have the even higher tensile strength needed to contain pressure. The the head and the brass in the wall near it must not be allowed to get anywhere near stress relieving temperatures (a band that starts at about 480°F).

Keeping the neck and shoulder at 570°F for an hour, while keeping the brass below the shoulder below 480°F would require some special equipment. It would also be painfully slow unless the setup was large enough for many cases.

The usual methods take advantage of the fact brass stress relief speeds up dramatically with increase in temperature. There is some loss of tensile strength from this, but the weakening effects of grain growth don't begin until about 660°F. Most methods go to 700°F-750°F, where grain growth is still very small, and accept a little of that in order to get done in a few seconds.

Much of the above is in Fred Barker's article in the July, 1996 issue of Precision Shooting Magazine, p.p. 90-92. The article makes much of the problems stemming from poor temperature control and mentions three workable methods to anneal without running over temperature.

One is to dot your cases with Tempilaq or to start them warming and to melt a little Tempilstick on them. You buy one rated for 650°F or 700°F for the neck. I use the former, figuring my flame will overshoot the mark a bit if it's a propane torch (fastest safe heat source). I might choose 700° for a candle flame or an alcohol lamp. The Hornady kit uses a lower temperature Tempilaq (475°F), but they have you apply it to the case below the shoulder and figure that once it melts you have done the job forward of that point. I've heard no complaints about it.

Barker's article cites the Tempilaq approach from an article by William Dresser in the September, 1962 American Rifleman that he says gets the metallurgy right.

Barker goes on to recommend two other methods as safe, which he does in one long sentence in all caps {I've not used the caps here}:
" (1) Lead Pot Method: heat lead to 725°-750°F; dip neck into powdered graphite and then—holding body of case in fingertips—into molten lead: when case body becomes too hot to hold slap case into wet towel; or

(2) Candle-flame method: Hold case body in fingertips, place case neck in flame and twirl case back & fort until case body is too hot to hold, then slap case into wet towel; wipe soot off neck % shoulder with dry paper towel or 0000 steel wool."
Here are a couple of other articles on the topic, FYI:

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


http://www.24hourcampfire.com/annealing.html
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Last edited by Unclenick; March 31, 2011 at 02:53 PM.
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