When To Anneal?

[JimSC]

For cartridge brass, the Young's Modulus of elasticity in tension is roughly 16000 kpsi and what moves around with the hardness values is the ultimate strength and the yield strength, as well as the percent elongation. JimSC is correct, the Young's Modulus for cartridge brass is fairly constant with the heat treat. When the material is work hardened, the modulus doesn't change much, but the hoop stress that will cause a yield or fracture will. When we hit a yield, then we are not going to get the same elastic tension.

So both sides of the argument are correct, but for different reasons.

that's partially true. Springs are not heat treated to make them more elastic but to improve their strength, this increases the extent to which they can deflect without deforming. The easy way to test to see if you are pushing past the yield point when seating a bullet is to size, measure the OD, seat a bullet, pull the bullet and remeasure. If you neck is still the same between the measuring before seating and after pulling you never hit the yield point when the neck was expanded by the bullet

elasticity is determined by strength of the atomic bonds. Atoms are pulled toward each other when the negative electrons of one atom attract the positively charged nuclei of it's neighbors. When an outside force attempts to separate the atoms it is is resisted by the changing electrostatic conditions. The resistance to separation is known as the elastic modulus. Strength and hardness on the other hand is determined at microstructure level. Annealing relieves the stress in the grain of the metal but at the atomic level the atoms never get closer together or further apart becasue of the sub atomic pushing and pulling of the electrons and protons. Therefor the modulus of elasticity does not change with hardness

Clear as mud right.

 

[rwj]

that's partially true. Springs are not heat treated to make them more elastic but to improve their strength, this increases the extent to which they can deflect without deforming. The easy way to test to see if you are pushing past the yield point when seating a bullet is to size, measure the OD, seat a bullet, pull the bullet and remeasure. If you neck is still the same between the measuring before seating and after pulling you never hit the yield point when the neck was expanded by the bullet

elasticity is determined by strength of the atomic bonds. Atoms are pulled toward each other when the negative electrons of one atom attract the positively charged nuclei of it's neighbors. When an outside force attempts to separate the atoms it is is resisted by the changing electrostatic conditions. The resistance to separation is known as the elastic modulus. Strength and hardness on the other hand is determined at microstructure level. Annealing relieves the stress in the grain of the metal but at the atomic level the atoms never get closer together or further apart becasue of the sub atomic pushing and pulling of the electrons and protons. Therefor the modulus of elasticity does not change with hardness

Clear as mud right.

BINGO!

 

[mikeeg02]

I can see you missed the entire point of the post. The neck tension is dependent on the elasticity which does not change with the hardness of the brass. Annealing changes the hardness but not the elasticity. I cannot put it more simply than that. Your personal anecdotes are fine but the science is what it is. I did not make those pages up out of thin air, they are engineering facts

So as a test I found some old 6br-improved brass that had never been annealed, and likely had 14-16 firings on them. First step was to run them through the sizing die (after having the necks cleaned inside and out). Cases were numbered, 5 cases used. Case number 5 had been fried a few times, as it was a piece when I started my annealing journey and initial testing. After sizing with a 263 bushing, I ran my expander into it, and let it loose in the case to measure the OD of the case, while on the .24075 expander mandrel.

All measurements taken with a mititoyo 0-1" mic, with friction stop.

Measurement on mandrel
1) .26340
2) .26335
3) .26330
4) .26325
5) .26300

Now for each case I pulled the mandrel, and remeasured.

1) .26280
2) .26270
3) .26300
4) .26280
5) .26260

Now I ran each case through the amp at the second to last setting I used on my match brass. (69 for those wondering) I then ran each case through the 263 bushing, and this time ran the expander into each case, and let it sit for ~30 seconds, which is similar to how long it took prior to remove the case and measure with the mandrel installed.

1) .26260
2) .26260
3) .26255
4) .26250
5) .26260

If annealing doesnt affect the spring back, elasticity, or whichever fancy word you decide to use, then why did my numbers change? And why did they get a whole lot more consistent?

Im all for professional research, and always respect people with way more intelligence than I have. It aspires me to run tests, and try new things I may not of previously thought of. I hadnt ran the numbers previously, I only knew the difference that I felt during seating, and what printed on paper. Now that I have ran the numbers, it sure does confirm what I thought I knew.

 

[JimSC]

If annealing doesnt affect the spring back, elasticity, or whichever fancy word you decide to use, then why did my numbers change? And why did they get a whole lot more consistent?

Im all for professional research, and always respect people with way more intelligence than I have. It aspires me to run tests, and try new things I may not of previously thought of. I hadnt ran the numbers previously, I only knew the difference that I felt during seating, and what printed on paper. Now that I have ran the numbers, it sure does confirm what I thought I knew.

I have no idea why, I just know the physics. I've heard it also impossible for bumble bees to fly.

You sound like a serious competitor who has been around a while so a question for you. How much better are the groups of today's shooters versus the groups before the AMP made it's debut? Remember the amp has only been out a couple of years now, before that the propane torch and a red glow was the preferred method, before that the candle till the case burned your fingers was all the rage. How much of a improvement in record scores in the last 5 years?

BTW as I have said before I am not a engineer or a top marksman. I don't mean to come off as either. I hung around my uncles machine shops a kid, worked there as a teenager. Did the Navy nuke thing after high school and did industrial refrigeration and AC till retirement. I just read a lot of engineering papers and asked a lot of questions from the engineers I worked with and for. Just been working with heat theory and materials properties most of my life. Amateur F class shooter with one year competition. I am here to learn

 

[Straightshooter1]

So as a test I found some old 6br-improved brass that had never been annealed, and likely had 14-16 firings on them. First step was to run them through the sizing die (after having the necks cleaned inside and out). Cases were numbered, 5 cases used. Case number 5 had been fried a few times, as it was a piece when I started my annealing journey and initial testing. After sizing with a 263 bushing, I ran my expander into it, and let it loose in the case to measure the OD of the case, while on the .24075 expander mandrel.

All measurements taken with a mititoyo 0-1" mic, with friction stop.

Measurement on mandrel
1) .26340
2) .26335
3) .26330
4) .26325
5) .26300

Now for each case I pulled the mandrel, and remeasured.

1) .26280
2) .26270
3) .26300
4) .26280
5) .26260

Now I ran each case through the amp at the second to last setting I used on my match brass. (69 for those wondering) I then ran each case through the 263 bushing, and this time ran the expander into each case, and let it sit for ~30 seconds, which is similar to how long it took prior to remove the case and measure with the mandrel installed.

1) .26260
2) .26260
3) .26255
4) .26250
5) .26260

If annealing doesnt affect the spring back, elasticity, or whichever fancy word you decide to use, then why did my numbers change? And why did they get a whole lot more consistent?

Im all for professional research, and always respect people with way more intelligence than I have. It aspires me to run tests, and try new things I may not of previously thought of. I hadnt ran the numbers previously, I only knew the difference that I felt during seating, and what printed on paper. Now that I have ran the numbers, it sure does confirm what I thought I knew.

Your results is what I would expect in that one gets that kind of consistency when there is less spring back. But . . . what about the seating resistance? Is seating resistance directly correlated to that sizing consistency? According to the science, that JimSC posted, it's not. So. . . need to see data regarding that seating resistance, huh?

 

[mikeeg02]

I have no idea why, I just know the physics. I've heard it also impossible for bumble bees to fly.

You sound like a serious competitor who has been around a while so a question for you. How much better are the groups of today's shooters versus the groups before the AMP made it's debut? Remember the amp has only been out a couple of years now, before that the propane torch and a red glow was the preferred method, before that the candle till the case burned your fingers was all the rage. How much of a improvement in record scores in the last 5 years?

Believe it or not, I'm also a relatively new competitor, but I enjoy the challenge of learning/adapting to what it takes to consistently shoot small, or as small as conditions allow. I can tell you I've come a long way in a very short amount of time. I have a very mathematical brain, geared towards problem solving. That's how I was raised and what I do for a living. Fix problems, usually ones resulting from engineers oversights of what happens in the field. Regardless. Looking at Williamsport's agg records, more and more people are keeping ten match aggs below ten inches. In ten match aggregates, none are thrown out. Conditions do come into effect, but on the good days the groups are getting smaller and smaller, and everywhere, not just Williamsport.

Not saying everyone is annealing, but many of the people I consider mentors and friends are, and I've found valid reason to look into it. As I said before, I'm not saying you can't shoot small without it, but it's certainly helped make things more consistent for me. As others have suggested to me. While the amp has helped me, there are other methods that utilize micro controllers with precision timing that are just as good, (and some think better) than how the amp does it. The amp is beneficial to me because I am able to use their spacers to easily repeat results with different case, and not try to setup the torches in exactly the same fashion.

I do enjoy reading everyone's opinion on things. No matter how small or trivial, or how new or seasoned a shooter. We all come to the table to accomplish the same goal. Shoot small. The benefit to seeing someone else's theories or concepts gives me new things to test or try, and a different light on things I may not of looked at or considered. The worst thing we can do is become narrow minded, and stop testing. No progress ever comes from that.

Also, I've read and looked at enough documentation on so many subjects to of learned to test what's written to see that field findings actually match the documentation. Just because an engineer said it's this way, doesn't mean in the field we achieve the same results. From the back ground you said you've come through, I am sure you've had similar findings. That's not always the case, but it's usually worth testing than to blindly follow what's written.

 

[mikeeg02]

Your results is what I would expect in that one gets that kind of consistency when there is less spring back. But . . . what about the seating resistance? Is seating resistance directly correlated to that sizing consistency? According to the science, that JimSC posted, it's not. So. . . need to see data regarding that seating resistance, huh?

I'll see if I can find some more old cases that I haven't annealed yet. I had to dig for the test subjects I used tonight. Cant hurt to do a little testing yourself. The more people testing the same thing, the more data there is to look at. And possibly more thoughts being put into the test.

 

[RegionRat]

I agree with mikeeg02, we should have had some legitimate research done on this by now, so we may as well get started.
The work hardening issue is separate from the issues that contribute to the tribology involved in affecting the bullet grip.

For example, when some folks use chambers that are tight neck, the amount of cold work per firing cycle isn't the same as a regular sporting chamber. The number of cycles required to hit a given hardness value is going to be different based on the chamber design and the user's sizing process. For example, I got away with more cycles between annealing and trimming with a Lee Collet die on my silhouette loads than I did with a conventional die, and I had lost far fewer to neck splits.

Never the less, it isn't difficult to set up a reasonable test where a case neck just gets work hardened by expanding it with a mandrel and then sizing it with a collet die or regular sizing die. The challenge is that measuring the effect of the work hardened bass is not an independent variable if the carbon in the necks is removed or worn off by mandrels and dies or cleaning processes. There is a typical Mu X N relationship for bullet grip and the Mu (Coefficient of friction) is very important.

Suppose we just size cycle brass and take the statistical approach to measuring seating force with sizing wax applied to make the friction coefficient reliable? This way, the control sample will only get work hardened and the other sample will get annealed.

In theory, if the work hardening changes the bullet seating force in some significant way, then the two types of samples won't track each other after many cycles.

My own theory is that the goal is to develop loads that are as insensitive to the grip, as well as charge value changes, as possible, such that annealing isn't the most important feature. Isn't that what we call a wide node?

The case cleaning and neck prep all play a role in addition to the annealing, so in the real world I imagine all those choices make this a very complex study by the time we factor in the time effect of storage on the metals of the case neck and the bullet jacket. I have personally measured the breakaway force of cartridges that were stored and seen the wild variation in values. Those necks had the same Vickers values when investigated, so the only conclusion I could come to was that while neck tension is important to manage, the neck cleaning prep can be far more important.

JimSC then asks the deeper question, if I may rephrase it here... when or if any of this makes an impact on group size? I think that also gets complicated by the concept that some systems are in a wide node and less sensitive, while others may show it immediately. I think a good rig that is cranking out 0.5 MOA is more likely to show the answers sooner than one that is only 1 MOA capable to begin with.

 

[JimSC]

Don't get me wrong I firmly believe that the AMP is the best home annealing system out there. But my ammo is a lot more consistent than my wind/mirage reading is. I don't think at this point in my shooting I could separate the chaff( me) from the wheat( rifle) when it comes to flyers. I already get low SD's and ES's and double digit reloads on my brass, so what exactly would it do for me that I am not already getting?

I get it that science and the engineers do not always have all the answers though. Hopefully one day AMP might give us some real tests not just pretty pictures of grain structure

 

[RegionRat]

Don't get me wrong I firmly believe that the AMP is the best home annealing system out there. But my ammo is a lot more consistent than my wind/mirage reading is. I don't think at this point in my shooting I could separate the chaff( me) from the wheat( rifle) when it comes to flyers. I already get low SD's and ES's and double digit reloads on my brass, so what exactly would it do for me that I am not already getting?

I get it that science and the engineers do not always have all the answers though. I once saw a machine once that the factory experts could not get to work for more than 5 minutes without a random shutdown until someone put a set of rosary beads on it as a joke, machine ran perfectly afterwards and no one dared remove the rosary beads for the two years I was there afterward. Still the facts are facts on material properties and the physics of material behavior are properties have been established a long time

I agree with you. There has to be a sensitivity to a given rig and load that makes the effort worth it. The arguments for and against annealing are similar to the ones for weight sorting bullets and brass. In theory, it is easy enough to test for it, but with annealing and case prep, it can get lost in the weeds.

 

[JimSC]

for whatever it is worth the Amp was released sometime in 2015 and there are quite a few 600 and 1000 yard records still standing which were shot previous to that

https://internationalbenchrest.com/records

 

[Straightshooter1]

I'll see if I can find some more old cases that I haven't annealed yet. I had to dig for the test subjects I used tonight. Cant hurt to do a little testing yourself. The more people testing the same thing, the more data there is to look at. And possibly more thoughts being put into the test.

You're right.

Only wish I had the right tools : http://www.mark-10.com/casestudies/Ammunition.html

 

[mikeeg02]

JimSC then asks the deeper question, if I may rephrase it here... when or if any of this makes an impact on group size? I think that also gets complicated by the concept that some systems are in a wide node and less sensitive, while others may show it immediately. I think a good rig that is cranking out 0.5 MOA is more likely to show the answers sooner than one that is only 1 MOA capable to begin with.

I dont think it has much to do with individual group size. A rifle can be tuned to different weather conditions, different distances, different stages of barrel life, and different stages of brass life. I do think it has everything to do with shot to shot consistency during the course of a cases life.

Annealing has been going in much longer than 2015, with equipment that when used properly is probably every bit as good as an amp, possibly better. (We all know the human error in things) I believe what annealing does is aids in making match to match consistency, over a piece of brass' life.

I'll repeat myself again and say that records and aggs can be shot without it. It's just a different tuning curve. Every time I previously tried it, it messed things up for me. It wasn't until I started from the first fire forming of the case, tuned with annealed cases and did it every time that I began to see its benefits. Previously it seemed to me that the more firings on my cases the more consistent they got. Now they have been consistent since fire forming.

And the poor guy who started this thread, only really wanted to know at what stage in his case prep since fired should he anneal.

 

[JimSC]

I'll repeat myself again and say that records and aggs can be shot without it. It's just a different tuning curve. Every time I previously tried it, it messed things up for me. It wasn't until I started from the first fire forming of the case, tuned with annealed cases and did it every time that I began to see its benefits. Previously it seemed to me that the more firings on my cases the more consistent they got. Now they have been consistent since fire forming.
.

just an anecdote but last year I installed a 6 CM barrel on one of my rifles, put 100 rounds down the barrel for break in then began shooting over the chrono. Found a middle node at 37.5 gns with an ES of 35 and a SD of 13 using once fired cases. Not the best velocities I have ever had but that weekend there was a 800 yard match and I had no time to fine tune so I ran with that load. Results were fair to middlin for me and and more consistent than what I normally shoot ( low to mid 190's). I shot it in a few more matches with my typical groups, low vertical spread and a wide horizontal mostly off center and dependent on wind conditions. What I call the ribbon effect. At around 450 or so round count I put the rifle up for a few months. Last week I shot it over a chrono using cases on their 5th reload and the ES had dropped to 17 and the SD to 8 using cases on their 5th reload. Alpha cases, 5th reload, Rem 9 1/2 primer, 2800 FPS velocity. There is another higher node around 2925 but the middle node works well enough and save the barrel a little. In this instance a few more rounds down the barrel and a little work hardening improved my results

One day I may buy a AMP or a AMP clone, but at the moment it is pretty low on my priority list. I just see no need for it whatsoever

 

[mikeeg02]

So you've found similar results. Though I dont use a chronograph for my testing, I go by variance in seating feel with an arbor press and I let the target grade my results or workmanship of loading. And as you found, your cases without annealing shot better as they accumulated firings. My difference is since I started annealing, my cases have been consistent since firing 1.

Another thing to remember, when we are measuring seating force, its not just the elasticity of the brass, the pressure ring is pushing the brass passed its yield, and then once past the pressure ring, the elasticity of the brass collapses onto the bearing surface of the bullet. The reason I say that specifically, is just like my test last night, the brass measured smallest before I pushed the expander into it. It was in the ~.261xx range IIRC. Then with the expander in it, it had a measurement of .263xx and with the expander removed it was .262xx. The size of the pressure ring in comparison to the bearing surface is different per bullet. And could likely skew the results of changing neck tension in either direction.

 

[JimSC]

well those 6CM cases should have been pretty work hardened after 4 firings and five loadings with no anneals. I was pretty happy with the velocity consistency and I would say that might be linked to a consistent neck tension. Now when I am shooting a 5K custom I might notice a difference but my old garage built Savages just don't seem to care one way or the other whether I anneal

As a nod to the OP when I did anneal I did it after depinning, sizing, and cleaning