Soldering iron for annealing?

I would highly recommend you not do this. Proper annealing assumes that you have the ability to rapidly transfer heat to the neck of the case without overheating the base or web area

Copper alloys transfer heat rapidly. It would be no different than the propane torch method except for speed. The torch should be decidedly faster as you are working with more heat. After all soft solder melts well below the heat require to anneal brass.The trick is knowing in when to remove the heat. Brass anneals between 650 and 700 degrees fahrenheit. The case neck will turn blue and the color will rapidly run down the case. As soon as the blue color appears on the neck remove the heat source. The color change will stop at or just below the shoulder of the case. Lots of factory ammo shows these colors if you need an example.

Get some Tempilaq and do some testing.

You need to get the two required temp's to monitor the neck and also verify the lack of "creep" to the rest of the case.

If you mounted the iron / tip to something like a drill press, you could control the depth & alignment while you run it into the case.

You could slide the case into a shell holder and all you would have to do is watch the Tempilaq.

This sounds like it could be a reasonably cheap experiment.

If you remove the heat when the neck turns blue the heat at the base might be a little uncomfortable to hold with bare fingers for a bit but will never get hot enough to affect the brass and that's with a case as short as a 223. Where the color change stops is where the annealing stops. I'm a little tone blind and see the color change start as a washed out silvery color and remove the heat immediately upon seeing that. After the flame is removed I can see the blue color plainly. I use a variable speed drill and socket and dump the case on a folded towel as soon as I quit heating. Dump them in water if you are worried about heat travel but you just add an extra step by having to dry them. I have turned them by hand wearing a glove just in case I let something slip but prefer the drill and socket as it's faster for me and I don't need to worry about slipping up and getting singed.

Only way to find out is try it. I get what you are thinking and the base wouldn’t be touched. You would need a solid piece of copper sized to the inside case neck. A soldering gun with a pencil tip would be best so you could have it tight in the center of the copper slug. If you have or have access to a metal lathe it would be a piece of cake to make a solid tip.
Thinking about this more whatever is used for the tip would have to be a tight fit in the neck or you would lose heat transfer and the hotter the better for quick heat transfer to the neck of the brass.

berettaprofessor said:

Yes, but as near as I can tell, anything at a 15W or higher soldering iron reachs 900F. I was hoping the variable setting would let me keep it around 650 and then just put brass on and off, neck first.

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When I use propane the flame temperature is just under 3600 degrees. And it takes five-ish seconds.
A nine hundred degree element would take longer, perhaps needing a heat sink for the head because of the time.

The flame anneals the neck quickly before the body can migrate the heat. More heat will reach the body and head, even though the temperature is lower, because the time will be so much longer with the electric element.

However, a tightly fitting element inserted by a press could very much anneal the brass.
I would try a form that could touch the shoulders from the outside as well, as these are what is sized for the chamber, the neck being for the bullet.

Interesting idea.

Melted lead, salt, fire, electric induction, conduction. Heck, even radiant heat would work with the right gloves.

If I was going to try something like this I would want a high wattage iron that I could control with a on/off foot switch/timer. Have the heating mandrel inside/or outside does not matter provide you can heat the brass up quickly and uniformly while controlling the heat. Which is what the Amp Annealer does. Having the heat on the inside will allow you to monitor it easier.

berettaprofessor said:

Yes, but as near as I can tell, anything at a 15W or higher soldering iron reachs 900F. I was hoping the variable setting would let me keep it around 650 and then just put brass on and off, neck first. I know it conducts fast but surely the case head won't get as hot as the neck until after the neck is too hot?

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The problem in your procedure, is assuming the iron can hold 900° or 650° when its being sinked by any object. Larger items like a chunk of copper or brass.... will sink a whole lot of heat, pass it throughout and pass it through the entirety of its structure.

Imagine this with your 900 degree soldering iron.... it makes 900° right? We should be good to go to solder a 3" heavy wall copper pipe with it then, right? Well of course not.

Call me old school, but... in the past, I've put an piece of angle steel on a brick. Next to the brick is a tray of water. The brass goes on the angle, the upright part of the angle "shields" the brass a bit from the flame. Mr. Burns-O-Matic does the heating, and when they're cherry (takes but a second), I twunk down into the tray with a stick and move on down the line of brass. Never had an issue, but.... ya know..... I've done mildly loaded cases that way, for 30-30 mostly. Things like .223/5.56 are so plentiful as pickups... I don't bother.

Trying to anneal a case properly with a soldering iron is like trying to put a new cable on the battery for your car with a soldering iron. It's not the right tool for the job. The correct tool is cheap easy to get and well proven. The consequences for getting it wrong are more than I would be willing to accept.

I actually tried this with one of my soldering guns today. Didn’t work that well and I have a much bigger gun than what you have. It has a single tip that fits snug into a 303 British case. Took a long time to heat the neck and just isn’t worth it
I do have one of these at work that I think would do it but it’s a little pricey though. Works like a hot darn on all kinds of rusted and seized bolts etc.

https://www.theinductor.com/induction-heater-tools/mini-ductor/models/mini-ductor-venom-hp-mdv-787

[double post

berettaprofessor said:

Anyone ever use a soldering iron for annealing? I’m thinking a variable temp unit like the Weller WLC100 and a tip custom sized to just slide into a given neck. It would anneal from the inside out (is that an issue?) but it could be pretty fast. Any thoughts or experience?

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Do not pursue this line of thinking. I use liquid salt bath, immersing the case neck-to-shoulder for 5 seconds at 500°Centigrade. Then drop the entire case in ice water to stop the heat-treating.