Annealed brass compared with new brass

[Known]

Folks,

Prior to taking the plunge on an annealing machine, I've been experimenting with some 750 degree Tempilaq and 7x fired Lapua .308 brass.

After annealing the brass with Tempilag applied INSIDE the case neck (rotating in the torch flame), I've noticed that it is nowhere near as soft as new Lapua brass. I also compared to some new Winchester brass with the same result. I subsequently turned off my lights and heated the brass until it just started to turn red (which is above 750 degrees) and found the result approximated new brass. I also went hog wild on a few cases until they glowed red with the lights on and sure enough you could crush them with your fingers afterwards.

This leads me to wonder what the proper temperature is for annealing brass in the context of reloading. Do we want it to be as soft as new brass or somewhere in between? There are equally authoritative tomes stating that heating the case neck to 650 for a few seconds is the right temperature versus 750. Similarly, some insist on water quenching while others do not. Some say the flame goes on the neck and others the shoulder, etc. This makes me wonder if there is a true understanding of how to properly anneal brass outside of the factory.

I'd like to hear from those with more experience annealing. Would be terrific to hear from somebody who works for a cartridge case manufacturer (Lapua, Federal, Winchester, etc.) as they must have this down to a science. So far everything I have heard is second hand knowledge. All the videos I've seen on Youtube are taken in somebody's garage - I'd like to see how they calibrate the annealing process at the factory.

Based on my personal experience, I believe the proper temperature may be above 750 when you are only heating the neck for a few seconds. I don't want to invest $500 in an annealing machine if I'm not doing any good.

Thanks....

 

[jrob300]

You're going to get all kinds of answers to that question...

The following is based on *empirical* results.

I too used Factory Lapua brass as my "standard" of how soft annealed brass should be. I found that slightly red to outright red in a dim/dark shop was required to get there. This is using MAPP gas from a pencil tip directed at the neck/shoulder junction. I use a Makita drill and chuck my brass in the drill and rotate over the flame. The chuck also acts as a heat sink. I then quench immediately in water.

I have used this technique on all kinds of brass. I even pushed the envelope and "over-annealed" a few cases. They demonstrated no different behavior than "properly" annealed cases, but even slightly under annealed cases were much harder than the control. So I tend to go longer than shorter.

Most interesting result of all this is that factory Winchester 300WM showed a measurable improvement in accuracy when virgin brass was annealed prior to firing. Makes me wonder how much "work-hardening" some factory brass sees *after* annealing.

John

 

[Known]

You're going to get all kinds of answers to that question...

Exactly - you hit the nail on the head. Everybody seems to have a different take on this. However, I would imagine there is more consistency among cartridge case manufacturers - that's why I'd like to hear from somebody working in that environment.

I'm going to order some 850 and 950 Tempilaq and see what sort of results I get.

If there is one consistent opinion it's that you don't want to anneal the head.

It has also been posited that too frequent annealing versus every 5-6 reloads might be bad because it burns out the zinc (or something like that) actually making the brass brittle. Again, all second hand information.

 

[waste_knot]

Do you have any type of hardness tester? Vickers, Rockwell?

 

[Known]

Do you have any type of hardness tester? Vickers, Rockwell?

I don't. Would be great to hear from somebody who does. Something along the line of: While heating to 750 may not appear to be as soft as factory brass, when you measure with (insert name of hardness tester) you are achieving the desired result because of (fill in the blank). Meanwhile, going beyond 750 will result in (fill in the blank based on such and such results from hardness testing) in addition to sterility, erectile dysfunction and other Biblical plagues.

 

[rm76]

Following this! Hard to distinguish science from fiction. Hope someone with authority will chime in.

 

[sinister]

5.56 (not 7.62):

Vickers Hardness Measurements of the M855 Cartridge Case Base:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA497469

 

[Known]

5.56 (not 7.62):

Vickers Hardness Measurements of the M855 Cartridge Case Base:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA497469

Perfect - now if somebody could measure Vickers Hardness based on 650 degree heating, 750 degree heating, etc.

Unfortunately, I doubt many reloaders will have this tool sitting around: http://en.wikipedia.org/wiki/Vickers_hardness_test

Perhaps some of the purveyors of annealing equipment (Giraud, Bench Source, etc.) have performed such tests.



http://en.wikipedia.org/wiki/Vickers_hardness_test

 

[Known]

Most interesting result of all this is that factory Winchester 300WM showed a measurable improvement in accuracy when virgin brass was annealed prior to firing. Makes me wonder how much "work-hardening" some factory brass sees *after* annealing.

John

Well there's another great question: Is annealing the final operation at the factory or are there additional operations that work harden the case?

 

[mdesign]

Interesting...wish I had access to a piece of equipment like that, be great to develop a measurable process.

I have experimented using Tempilaq up to 900 deg, at that temp the necks seemed softer than my Lapua brass. FWIW, I use 650 and do not water quench, just air cool. I used to have split neck issues on my 300WSM but not any more @650.

 

[Known]

I sent a message to Giraud and Bench Source along with a URL to this thread to see if they have any comments.

Here is the Bench-Source manual (http://www.bench-source.com/sitebuildercontent/sitebuilderfiles/annealerrevb.pdf) - they recommend heating to 650 degrees. Starting on page 7 they provide some general information about the annealing process.

Here is the Giraud manual (http://www.giraudtool.com/Annealer IB.pdf) - they recommend heating to 750 degrees.

Hopefully one or both of the vendors can explain what they base their temperature recommendations on. Also, how should brass annealed per their recommendations compare to new brass?

 

[Known]

I have experimented using Tempilaq up to 900 deg, at that temp the necks seemed softer than my Lapua brass. FWIW, I use 650 and do not water quench, just air cool. I used to have split neck issues on my 300WSM but not any more @650.

At 900 degrees, do the necks start turning red / maroon?

 

[jrob300]

Well there's another great question: Is annealing the final operation at the factory or are there additional operations that work harden the case?

Annealing *can't* be the final operation if the brass is not discolored. Lapua is perhaps the only brass mfg. that I know of that does NOT clean after annealing. It is typically the last operation I perform as well.

John

 

[mdesign]

Yes, they were turning red but it was a little hard to time it just right as I had difficulty watching the paint melt in the light of the torch and also watching the color of the brass. To me, watching the change in neck color while using a torch in a dimly lit room in not easy to do consistantly.

Annealing at 650-750 F does not discolor my brass. I only anneal clean sized brass, it is my final operation and it slightly deepens the golden brass color.

 

[softcock]

quote
...." Most interesting result of all this is that factory Winchester 300WM showed a measurable improvement in accuracy when virgin brass was annealed prior to firing. Makes me wonder how much "work-hardening" some factory brass sees *after* annealing ".
-----

Also Found that out, & Started that a few years ago with Annealing New Win. .33WM brass . I got great constant neck tension after that w/ Better accuracy .
Also I take once fired Fed.Brass & anneal . Then body-only & then neck-size . the stuff shoots great.

So (imho) I also think some brass is just over worked in the steeped proses of making it .
.

 

[Known]

So I received this bit of information in a private message:

http://www.substech.com/dokuwiki/do...ass&DokuWiki=743672b2f72c2583bbb1903c1f3fe0e0

And an explanation:

This reference shows the annealing temperature of the material to be between 800-1400 degrees F. Since the reaction time of any temperature measurement system will be slower than actual temperatures achieved for thin cross sections, round down to 750F knowing the heat source will overshoot the desired indication temperature by some margin. Higher temperatures will most likely cause a separation of the zinc from the copper in the solid solution. Greater than 750F but lower than 800F will still cause a substantial stress relief even if the base material does not fully achieve the 800F transitional temperature to reform the grain structure of the material.


My thoughts going forward:

So I'm going to see how many firings I get out of my Lapua brass before a neck split. Historically, I've encountered head separations first when aggressively resizing. These days I still FL resize but just push the shoulders back 1-2 thou.

I'll take the other half of the lot and anneal at 750 degrees every 5 reloads and see if there is a difference.

I'll report my observations, although it may take some time.

 

[jsthntn247]

Please post back on your results, I'm definitely interested in hearing them.

 

[fish30114]

Well I am in the school of thought that is - 'do what works for you' - I anneal every fourth or fifth firing using the Tempilaq that came with the Hornady annealing kit. Basically 3 different size case holders, do the same thing as an aprropriate sized socket would do. Came with 475 degree Tempilaq. You paint that on the neck shoulder junction and stop heating when it melts. I put the tip of the blue point of the 'inner flame' on the neck shoulder junction and get a count with a digital metrenome (sp?) and get in a rhythm on the count. It is typically about 10 to 12 count with '06 family cases being more like a 10 count, and WSM cases and Dakota cases being a 12 count.

Now that is counting to 10 or 12 out loud, (or in my mind) not a measured 10 or 12 seconds. Long story short, I track my cases diligently, and I have a group of 308 cases that is on over 55 loadings. Now that same rifle with a set of the same MFG cases that were not annealed developed neck tension issues around the 8th-10th loading and developed some neck splits around loading 13-14. I also anneal a fair bit of nickel plated cases and I find that to anneal them fully, which I judge by the feel in the sizing die, and springback they exhibit--measured-- they take an extra 2 count.
I realize this isn't very emperical, but I figure Hornady has a good reason for selling the kit with the 475 degree stuff. And I find from experience it works. I don't quench though, which the Hornady kit recommends. This method gives me the results I am looking for, and yes, in comparing accuracy with and without annealing I have found there is definitively more accuracy for me with the cases I have annealed--even more so than virgin firings. Of course YMMV

 

[ChadDoe8]

I put my brass on a bamboo bar-b-que skewer (through the primer pocket) and heat the necks in a dark room just until they turn red. I then dump them immediately in water. This results in dead soft brass at the neck and shoulder but still good and strong at the head. My understanding is that if you over heat the brass you are actually burning off the zinc and this can lead to less case strength and shorter useful life.