Annealing Cases

[Buffalobob]

Three videos on annealing cases

Video #1


20090312082212.flv video by bufflerbob - Photobucket

 

[Buffalobob]

Video #2


20090312104425.flv video by bufflerbob - Photobucket

 

[Buffalobob]

Video #3


200903121054372.flv video by bufflerbob - Photobucket

 

[jmason]

BB thanks for the video! I also appreciate the "how to" on collecting home owners insurance funds.

 

[Broz]

Thanks for posting this. I have a few questions if I may. 1: do you tumble before or after or both? 2: can you post a pic of the finished product? and 3: if you get some cases hotter than others (with in reason) will it affect the finished neck tension?

Thanks!

Jeff

 

[Buffalobob]

Broz

I normally tumble after annealing. A little carbon does not bother the temperature of the brass.
I tried to take a few pictures a couple of minutes ago but I could not get them to show the discoloration that exists. It looks just like what you see on a brand new Lapua case. The discoloration goes away with tumbling.

As far as getting the cases too hot, what I can tell you is that it is not as bad a problem as not annealing in the first place. One of the things about shooting competition with a 308 at 1000 yards is that any bug or flaw in your reloading process shows up big time. Faster cartridges camouflage your reloading errors. My life does not revolve around my scores in competition but rather around my hunting so I am somewhat sloppy and lacksadaisical with my reloading. I probably only anneal about once every four firings and that seems to be the point in which I can detect accuracy problems with the 308 at long range.


Finally, I am not any kind of expert on annealing but I just wanted to make some videos that would take the mystery out of it and help other people see how easy it is.

The other thing that helps case neck tension is using a bore brush in a drill on the inside of the neck after each firing.

 

[Broz]

I am just prepping brass for the fifth firing. I am sizing with Redding comp bushing dies and have been using a bushing that only gives me about .001" tension on the neck. I just started to notice with the 5th sizing that it seems to not be enough. I was just going to drop down a bushing size ot two and go again. Question is, will that work or am I in need of annealing? If possible I would like to wait one more round and anneal next time. But I don't want sacrifice any accuracy.

Thanks!

Jeff

 

[jmason]

Bob will have a better more knowledgeable answer but I'll take a stab.

I think you do need to anneal. You may get away with stepping down a bushing size but you run the risk of splitting necks(when fired after this sizing) and ruining the brass. You may know already how many firings you can get away with before that happens. I have had splitting on the fifth firing in the past. I don't enjoy the whole brass prep deal, so anything I can do to avoid those 1 time only tasks with prepping brass, and stretch case life is good. I am new to annealing but I can tell you it's not difficult at all as BB has shown you. You may ruin a piece or two the first time you do it and that's about as bad is it gets. You can see in BB's video you only need heat on the brass for about 4-5 seconds. When it looks like the brass is about to set fire (note the flame about to start in the video just before he pulls the brass out of the fire)your done.

 

[Broz]

Makes sense. Another Q. If I understand correctly this process is to soften the brass which has become hard from working it and firings. Wouldn't the rapid cooling affect of the water make it harder? I always thought a slow cooling process would make things soft and a rapid cool hardens them?

Jeff

 

[jmason]

Makes sense. Another Q. If I understand correctly this process is to soften the brass which has become hard from working it and firings.

Jeff

You understand correctly here

Wouldn't the rapid cooling affect of the water make it harder? I always thought a slow cooling process would make things soft and a rapid cool hardens them?Jeff

I can't give you an intelligent answer here. BB or one of the other guys will certainly know.

I just wanted add to my statement about "when you see the brass starting to catch fire". I based that on the use of a "templestcick" the first time I tried annealing. The templestick melted at the same time the brass looked like it was about to go up in flames(4-5 seconds). So now I used that timing and visual to gauge completeness in stead of the templestick which is a bit combersome.

 

[Buffalobob]

I am sizing with Redding comp bushing dies and have been using a bushing that only gives me about .001" tension on the neck. I just started to notice with the 5th sizing that it seems to not be enough.

That is the exact symptom of the need to anneal. If you don't anneal your bullets will spray all of the country side at long range.

Dumping the cases in water is the old fashioned time honored way of doing it. People who have an air compressor and need to justify having bought will just blow compressed air on it and the people with the little daisy wheel automatic things just let them air cool. Apparently it the cooling part is not as critical as say quenching a metal knife blade.

 

[Buffalobob]

I will simply add that even if you do overheat the necks that the brass is still fine.

I anneal my brass just as I showed including the goof ups. Last weekend at F-class my daughter came in second in F/TR and actually had more Xs than the one guy who beat her. She fired a center fire rifle for the first time exactly a year ago. If you read Shawn Carlocks article on fitting stocks--- well she is shooting a stock that fits a man so she is already handicapped with a bad fitting stock and still out shoots most men (including me).

The method that Kirby recommended works very well for casual competition and extremely well for killing animals. Few people on this forum can match the results on animals that has been obtained with brass annealed by the method I show.

It's not rocket science --- just heat it up to dull red and dump it in the water If it get cherry red just curse once and dump it in the water.

 

[loaders_loft]

Makes sense. Another Q. If I understand correctly this process is to soften the brass which has become hard from working it and firings. Wouldn't the rapid cooling affect of the water make it harder? I always thought a slow cooling process would make things soft and a rapid cool hardens them?

Jeff

Jeff, your question involves a bit of metallurgy (science of metals). I didn't get an A in metallurgy, but I did pretty well in the lab. I'll attempt to explain, hopefully I can remember what Dr. Forgeng & Dr. London taught me...

You're thinking is correct, for carbon steels, because of phase changes and precipitation of a secondary phase.
However, cartridge brass is different.

Cartridge brass, (alloy C260) is 70%Cu (copper), 30%Zn (zinc). It is a single phase alpha FCC structure, from room temp to about 1700F. Therefore, temperature cycling at/below this range does not produce a phase change or precipitation hardening.

Cold working (forming, sizing, etc) breaks up the grain structure in the brass, which blocks dislocation motion (structure defects) thereby increasing the yield strength and hardness. Although firing is still considered cold working, it has less effect than our normal reloading procedures of forming, sizing and seating.

The process of annealing cartridge brass recrystallizes the grains into new strain-free grains about the same size as the original grains prior to cold working. The grain size after recrystallization is more dependent on the degree of cold working, than on the annealing temperature.

The rate of re-crystallization is governed by temperature and the degree of prior cold working. However, long periods of time at lower temperature can recrystallize also.

The purpose of the quenching is to stop the recrystallation process prior to grain growth (bad).


lightbulbThat's the "Book Learning", which nobody really cares about anyway.

We really just want to know how to anneal the brass and not ruin it in the process...

 

[Buffalobob]

After much editing, I managed to get the color change to show up in the photos I took. The cases on the right have just been annealed. The cases on the left were annealed last month and have been fired once and all traces of color are gone. You will notice the color change from annealing goes a little way below the shoulder and stops. It varies for two reasons:

1. Exactly where the case is in the flame changes each time I anneal a case

and

2. If you go fast like I was doing with a hotter flame you will get more temperature variation in the brass.