Repeated Annealing

[Keith Glasscock]

I have a question for the metalurgists out there...

I know that firing a case and resizing it causes work hardening. I know that case necks need to be a given temper (for lack of a better word in my vocabulary) i.e. not too soft. I know that over annealing (either too much heat or too much time) makes case necks too soft. I also know that several really good shooters are annealing every reloading, but I am curious...

If I were to anneal a case, forget that I did it, and anneal it again, say 2 days later, would it be softer than if it was annealed once? Likewise, if I take 4 times fired brass and anneal it properly, then fire it once and anneal it again, would it be softer the second time (because it wasn't as work hardened)?

I'm trying to plan how I'm going to integrate annealing into my reloading routine. I have a repeatable annealing machine that I'm using on my 4 times fired cases, but I've found that I need to do it more often than that. I'm just wondering if I can get myself into a "too soft" situation...

 

[thefitter]

I hear it happens with age. ;D

But seriously those are all great questions I too would like answered.

 

[necchi]

IF the brass is brought to the same temp for the same amount of time ,,
each time it's annealed.,,
You could anneal it every hour if you wanted too and it would be no softer than the first time you did it.
Annealing sett's the matrix of the brass molecule structure, Time and Temp determines the form of this matrix. Change the time and temp and you change the matrix.

I load for a friends 223wssm with a chamber that requires a full FL sizing for the brass to fit each time. If I don't anneal the necks each time before sizing,, they'll split :

 

[Keith Glasscock]

Thanks Necchi,

Following your logic, if I had some cases that were otherwise identical except the annealing, then I fired them and annealed them all together as a batch, they would then be all the same...?

 

[necchi]

Only as it applies to the softness/hardness of the neck and shoulder area.

Other conditions of the brass age such as number of shot's fired and sizing issues can effect the body and primer pocket. Know what I mean?

Repeated FL sizing can stretch the body and begin creating the dreaded case head separation thinning , Heavy charges can lead to the primer pocket getting loose, olde and random range pick up can have corrosion issues,,,

At my house I keep brass (even the same head stamp) isolated in groups ranked by the # of loading/firing so I can keep an eye on general condition of the group.
I tend to use heavier charges at times, loose pockets are the bain to my brass. If a primer slides in just a little too easy the case is marked for it's final firing and tossed in the scrap bucket.

 

[Keith Glasscock]

Same system here. In my case, I pulled a bone-headed organizational stunt. I put cases in the wrong bag and had to sort them back out (fortunately, they were significantly different in weight). Unfortunately, they were annealed and sized with the wrong lot of brass.

Even though I get really consistent looking results, I know that every time I turn the torch off and relight it I get a different annealing result - even though I can't detect it. Thus, I am keeping the "oops" brass separate from the others. My question was whether I could recombine the lot after firing.

I have become quite fond of Sharpie paint pens. They make excellent primer markers (paint in the groove) that I can see even after case tumbling. My "disposed" match cases get a little different treatment than yours. I have found that I dispose of cases 1-2 firings before there is any sign of primer leakage, so the cases that the primer pocket worries me are checked to see if they will hold a primer. If they will, they get loaded for varmint use (one shot) before being relegated to the annealer setup pile. After they serve their purpose with the annealer, they get put into the recycle bucket.

 

[necchi]

Good point, annealing isn't the magic wand that makes cases last forever.

 

[lpreddick]

since we cannot view the microscopic changes that seem to take place during annealing, we have ONLY the color changes to know that annealing took place. the microscopic rearrangement of the metallic "latticework" seems to be what is happening. how many firings or how long does it take before the changes revert and harden the brass to the point we see neck split? i serously doubt only one firing of an annealed case will cause this change. a timed exposure to whatever temperature cannot assure us that annealing has taken place...only color changes in the brass. the beautiful grey/bluish/metallic change in the neck to shoulder to upper body leaving the dark bluish/reddish orange ring, then normal brass color is what i've seen on lapua brass and is what i've been able to produce with a propane torch while spinning a case. this change may be the ONLY way we can feel we have annealed. an experiment we can all try: some cases anneal quickley and nicely(the above color change). take one of these cases, polish off the noted color change, fire the case and see if you can "anneal" it the same day. i doubt we will see the same changes. i suggest that a truly annealed case needs either time or several firings before micrscopic changes occur to the point that they will respont to annealing temperature.

 

[Heavies]

I do my brass after 3 firings. I do this by hand, and use the color method. My brass, 6br, has lasted many reloads, however, this is by no means consistent, and I have on order a machine to bring things into consistency.

How do you very experienced annealers determine the correct time/temp for correct annealing of the brass case? Tempelaq, color, combination of both?

Also, I would think that annealing after each firing would be best for consistency. I intend to do this once I have the machine setup.