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Is it worth it to anneal twice - once before and once after resizing?

Should you clean fired brass inside and out (like tumble) before you anneal ? Is there any harm in heating the carbon in the fired case ?
 
The second annealing would be to get the brass back to the pre work-hardened state. Per the AMP research, annealed brass has a hardness of roughly 98HV if done correctly, once it is sized, the number increases to about 125HV and then to 150HV when fired. Annealing would restore the brass to 98HV, similar to virgin brass and also resetting any inconsistencies in working the brass that I may have introduced in the resizing process. There may also be a fair bit of tail chasing form my side....
If someone can actually shoot the difference between case necks with a consistent hardness of 98HV and 125 HV, then perhaps annealing twice might be useful for them. I cannot. As long as the annealing step is complete, and performed at the same point in the brass prep every time, the brass hardness will be consistent from prep to prep, and it should shoot consistently from prep to prep.
 
Annealing before and after resizing is counterproductive. After the first annealing the brass is in a recrystallized state. Residual cold work is minimal. During the sizing process you do NOT put enough cold work into the brass to have a recrystallization temperature that the AMP can get to without reprogramming. THERE IS A TIME AND TEMPERATURE REQUREMENT. Low cold work higher temperature and longer time. This is also why annealing at low temperatures and “every firing” is also counter productive. This has all been documented here if you search the archive and is well known in metallurgy.
So, are you saying it is not good to anneal after each firing?
 
annealing every firing is not warranted.
While I agree, I speak for my purposes - extending brass life by mostly eliminating split necks. I don't think I or my rifles can shoot the difference in the neck tension of anneal every time vs every 3-4 times. But I don't doubt that there are folks who can shoot that difference and may need it to compete.

And, I do take measures to reduce cold working by proper size bushings or body die + collet die.
 
It depends on how much cold work you put into your brass each firing cycle. If your using a bushing sizer, only pushing the shoulder back .002 and sizing the neck without an expander... then no, annealing every firing is not warranted.
I did a small experiment earlier. I took some .260 cases that had not been annealed for at least ten firings since I stopped annealing about two years ago. Using my Annealeeze I annealed ten and sized them and took ten that were not annealed and sized them.

Before sizing the neck ID was .265. After sizing they were .261 I seated a bullet then pulled it. Of the ten that were annealed the neck sprang back to an ID of .262, of the ten that were not annealed the ID after seating and pulling was .263. Twenty cases may not be statistically significant but it was enough to indicate a trend. I am not sure how that will translate to the target but it did show me that stretching that case neck .003 went beyond the elastic phase and into the plastic phase on those particular cases which after ten plus firing were well work hardened.

I will load twenty annealed and twenty non annealed later today and will set up at either 300 or 600 depending on the wind conditions to see if one group or the other has any or the most "what the heck" flyers. I can generally stay under a MOA with steady wind but get the occasional shot that hits 1.5 MOA or more away from POA. I know that is not not very scientific but it will be good enough for me to decide whether I want to start annealing again on a regular basis
 
It depends on how much cold work you put into your brass each firing cycle. If your using a bushing sizer, only pushing the shoulder back .002 and sizing the neck without an expander... then no, annealing every firing is not warranted.

That has not been my experience. Either anneal after each firing or don't anneal at all. The worst thing we can do is anneal every few rounds.

When we anneal after every firing we get the brass to a reasonably consistent state. My evidence for this is the high level of consistency I see when seating bullets on my hydro seater.

With brass that isn't annealed at all, I have less consistency in seating pressure and thus more sorting to do.

I have shot equally well in LR BR with brass that was annealed every firing and brass that hasn't been annealed at all, but with either method I am only shooting rounds that have the same seating pressure. The outliers become sighters.

Annealing every few rounds means there is a bigger change after each annealing. That means the tune needs to be rechecked and probably adjusted. In LR BR we are constantly tweaking our tune so it's not hard to adjust for that. However, when we are unable to recheck the tune before a match it's important to have as much consistency as we can get.

The reason I choose to anneal every firing is because my seating pressure is more consistent, there is potential for the brass to last longer, and it's very quick to do with an AMP.
 
That has not been my experience. Either anneal after each firing or don't anneal at all. The worst thing we can do is anneal every few rounds.

When we anneal after every firing we get the brass to a reasonably consistent state. My evidence for this is the high level of consistency I see when seating bullets on my hydro seater.

With brass that isn't annealed at all, I have less consistency in seating pressure and thus more sorting to do.

I have shot equally well in LR BR with brass that was annealed every firing and brass that hasn't been annealed at all, but with either method I am only shooting rounds that have the same seating pressure. The outliers become sighters.

Annealing every few rounds means there is a bigger change after each annealing. That means the tune needs to be rechecked and probably adjusted. In LR BR we are constantly tweaking our tune so it's not hard to adjust for that. However, when we are unable to recheck the tune before a match it's important to have as much consistency as we can get.

The reason I choose to anneal every firing is because my seating pressure is more consistent, there is potential for the brass to last longer, and it's very quick to do with an AMP.
Ok, I can see why folks anneal at LR.

A question I have is how many wind flags do you use?

Thanks
Dave
 
You are presuming that seating pressure is a measurement of bullet release. I submit that there is scant evidence that seating pressure is a direct measurement of anything other than seating pressure. Now if the mechanism of bullet release is the inverse of bullet seating (and there isn’t much evidence that is the case) what about the variances in bullet engraving? How does it affect ignition (or does primer variance have more effect)? There’s a LOT more variables that affect shot to shot performance...

as for the metallurgy, like I said, there’s a minimum cold work and time and temperature requirement. And each time you anneal you ARE CHANGING your microstructure.
 
Ok, I can see why folks anneal at LR.

A question I have is how many wind flags do you use?

Thanks
Dave

During a match there are usually a half dozen primary range provided flags that are 10-12 feet up. There are also a handful of smaller flags that shooters bring.
 
You are presuming that seating pressure is a measurement of bullet release. I submit that there is scant evidence that seating pressure is a direct measurement of anything other than seating pressure. Now if the mechanism of bullet release is the inverse of bullet seating (and there isn’t much evidence that is the case) what about the variances in bullet engraving? How does it affect ignition (or does primer variance have more effect)? There’s a LOT more variables that affect shot to shot performance...

as for the metallurgy, like I said, there’s a minimum cold work and time and temperature requirement. And each time you anneal you ARE CHANGING your microstructure.

Your assumption about my presumption requires an injunction....... ;)

Variances in seating pressure can be caused by several things:
- If the necks aren't cleaned seating pressure increases
- Differences in internal neck diameter (neck tension) will show up as changes in seating pressure
- Differences in bullet diameter can show up as changes in seating pressure

My understanding is the neck expands off the bullet before the bullet starts moving forward very much if at all. So as long as there is proper neck clearance in the chamber, seating pressure caused by neck smoothness or cleanliness won't affect bullet release.

However, neck tension is an important part of tuning a highly accurate rifle, and variances in neck tension show up as variances in seating pressure.

Also, variations in seating pressure often result in variations in seating depth, and inconsistent seating depth can affect accuracy.

At the end of all this, most of those who I shoot LR BR with use a hydro seater and make a final sort by seating pressure. It helps us shoot small groups at long range.
 
I decide to take my little experiment farther. I do not have any new 260 Rem brass but I do have some new Alpha 6.0 Creedmoor as well as some 6 Cm that had 9 firings on it never annealed so I used it.

Results from the annealed and new. Both had the brass sprang back .002 versus the non annealed .001.

That raised a new question whether stretching that neck brass circumference .1 inches took the brass from the elastic to the plastic deformation phase. It makes me wonder if sizing down farther than .002 does anything, even on new brass or annealed has any more of a compression effect than .002. In other words did the brass reach yield point when inserting the bullet and stretching that brass. It also showed me that annealing does affect resizing since without fail the brass that was thoroughly work hardened only sprang back .001 vs .002 before annealing
 
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