Old Brass = Lost Accuracy. Why?

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prickett

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Mar 21, 2019
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#1
Recently, my accuracy has been plummeting. I figured maybe my technique had slipped. But the other day I didn't have enough of my regular brass cleaned and annealed, so I loaded up some rounds using some once fired brass that a friend gave me. I started out shooting my regular brass rounds and was depressed with my accuracy. My group sizes were probably triple what I used to get. I then loaded up the rounds with the once fired brass. I didn't expect much, not having ever tested loads with it. Boy was I wrong. Suddenly my tight groups returned. So, my question is what is going on with my old brass? I started salt bath annealing my brass for the past 3 times I've used the brass (probably had 5 or more unannealed shots through it before I took up annealing).

I talked to an experienced long range shooter who suggested it might be because the necks need turning. Does that sound likely? Reasonable? Or, is there something else I should try?

They easiest (pre-drought) solution would be buy new brass. That isn't an option now.

EDIT: Timeline of events
1st few shots through brass (maybe 1st 5 uses): Great accuracy
Next few shots through brass: Group size probably tripled
Tried salt bath annealing to solve problem
Shots after annealing: No change to group size (still triple original size)
 
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#2
Are you sure your salt bath anneal is enough?

I did have a batch of old Winchester brass with a ton of firing on it that kinda went to hell, it had all been neck turned when new.
I turned the necks again and it a surprising amount came off and it shot great again till the pockets eventually started failing.
It was more an ES issue than a accuracy issue for me though.
 
#3
I would guess annealing changed the composition of your brass some. Neck turning may work, but if you annealed the necks may to be too soft, it could go the opposite way and make it worse.
I would fire the brass once, don't anneal, then when sizing it, try adjust your neck tension, either seating force or by caliper. Don't size-process all your brass at once, do 10 and test, if not there, change it up. My suggestion is tighten the tension.
 
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#4
You killed your brass by annealing.

Here is what I have found by accident:

I have a great load. I anneal the case and the load falls apart. I go back to unannealed brass and the accuracy returns. I pull the bullets from the annealed brass and resize the necks. I put the brass aside for fouling shots.

The next time I shoot I shoot the annealed brass first to foul the bore. They shoot tight groups.

WTF?

So I go back and rethink this and suppose that the act of seating the bullet, then pulling it, then resizing the neck, and seating the bullet did something to the neck. But the expander mandrel should have done that. But the expander mandrel is .306” and the bullet is .308”. Something about expanding the neck to .308” then sizing it back down to .306” fixed the neck. Maybe hardened it a little. Maybe introduced some stress in the brass. Maybe a totally stress relieved case is bad for accuracy?

I read some people like to take new factory brass and run it through a std FL die before they load it. Maybe there is something to that because it seems to bring cases back to life.
 
#5
Steel head said:
Are you sure your salt bath anneal is enough?

I did have a batch of old Winchester brass with a ton of firing on it that kinda went to hell, it had all been neck turned when new.
I turned the necks again and it a surprising amount came off and it shot great again till the pockets eventually started failing.
It was more an ES issue than a accuracy issue for me though.
Click to expand...

I don't understand what you are asking when you say "Are you sure your salt bath anneal is enough?". Are you saying it wasn't annealed long enough? Or something else?

Your antidote suggests that neck turning was the problem with your old batch of brass, correct?
 
#6
Milo 2.5 said:
I would guess annealing changed the composition of your brass some. Neck turning may work, but if you annealed the necks may to be too soft, it could go the opposite way and make it worse.
I would fire the brass once, don't anneal, then when sizing it, try adjust your neck tension, either seating force or by caliper. Don't size-process all your brass at once, do 10 and test, if not there, change it up. My suggestion is tighten the tension.
Click to expand...
That sounds like a good plan!
 
#7
918v said:
You killed your brass by annealing.

Here is what I have found by accident:

I have a great load. I anneal the case and the load falls apart. I go back to unannealed brass and the accuracy returns. I pull the bullets from the annealed brass and resize the necks. I put the brass aside for fouling shots.

The next time I shoot I shoot the annealed brass first to foul the bore. They shoot tight groups.

WTF?

So I go back and rethink this and suppose that the act of seating the bullet, then pulling it, then resizing the neck, and seating the bullet did something to the neck. But the expander mandrel should have done that. But the expander mandrel is .306” and the bullet is .308”. Something about expanding the neck to .308” then sizing it back down to .306” fixed the neck. Maybe hardened it a little. Maybe introduced some stress in the brass. Maybe a totally stress relieved case is bad for accuracy?

I read some people like to take new factory brass and run it through a std FL die before they load it. Maybe there is something to that because it seems to bring cases back to life.
Click to expand...

The reason I started annealing in the first place was because my many fired brass had lost accuracy, so I'm wondering if annealing worsened the problem or just didn't fix the problem. My accuracy after annealing doesn't seem worse, it just isn't better.
 
#8
prickett said:
The reason I started annealing in the first place was because my many fired brass had lost accuracy, so I'm wondering if annealing worsened the problem or just didn't fix the problem. My accuracy after annealing doesn't seem worse, it just isn't better.
Click to expand...
In shooting, sometimes changing one small thing can make a huge difference for the better, primer swap, powder charge adj, seat depth change, etc...
But when you alter something(anneal), again, a tweak may be needed. 918 was correct, you can reharden brass by working it. Just try adding some neck tension on a few.
 
#9
prickett said:
The reason I started annealing in the first place was because my many fired brass had lost accuracy, so I'm wondering if annealing worsened the problem or just didn't fix the problem. My accuracy after annealing doesn't seem worse, it just isn't better.
Click to expand...

I have always gotten best accuracy from 1x, 2x, 3x fired brass. I’ve gotten the worst accuracy from annealed brass. I’m not a metallurgist but what I understand about annealing is it removes all the stress and rearranges the grains in the brass. I know that the way brass releases the bullet is critical to accuracy. My goal is to recreate 1x fired brass. Because there is something about 1x fired brass that produces one hole groups for me.

Take your annealed necks and work them. Also, make sure they are dry lubed. Don’t seat bullets against bare necks after annealing.
 
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#10
prickett said:
I don't understand what you are asking when you say "Are you sure your salt bath anneal is enough?". Are you saying it wasn't annealed long enough? Or something else?

Your antidote suggests that neck turning was the problem with your old batch of brass, correct?
Click to expand...
Yes
I’m curious if it’s under annealed or if it substantially more
Maybe something changed?
Similar seating for to other batches or from case to case?

yes, neck turning helped return my brass to how it was shooting.
 
#11
Steel head said:
Yes
I’m curious if it’s under annealed or if it substantially more
Maybe something changed?
Similar seating for to other batches or from case to case?

yes, neck turning helped return my brass to how it was shooting.
Click to expand...

Given that the results don't seem different between the poor groups before annealing (after 5 or so firings) to the equally poor groups afterwards, I'm thinking it isn't the annealing that is to blame.

The experiment between the 1 fired brass and the many fired brass, where the 1 fired gave MUCH better results, the cartridges were loaded in the same session using all the same things: same bullet, same powder/powder weight, same sizing, same seating depth. Everything was the same except the resultant group size.

How much did neck turning help? What size groups do you go from to?

Based on previous answers, there are several experiments I need to try.
 
#13
prickett said:
Given that the results don't seem different between the poor groups before annealing (after 5 or so firings) to the equally poor groups afterwards, I'm thinking it isn't the annealing that is to blame.

The experiment between the 1 fired brass and the many fired brass, where the 1 fired gave MUCH better results, the cartridges were loaded in the same session using all the same things: same bullet, same powder/powder weight, same sizing, same seating depth. Everything was the same except the resultant group size.

How much did neck turning help? What size groups do you go from to?

Based on previous answers, there are several experiments I need to try.
Click to expand...
As I said earlier
I didn’t have group issues
My Extreme spread got bad.

I still suspect your annealing process.
 
#16
Precision Underground said:
Some say salt bath doesn’t work well/at all. I’d say your only shot is to hope it’s under annealed and try a different method. What caliber brass is it?
Click to expand...

As mentioned previously the accuracy problem started before I ever annealed. I tried annealing to solve the problem. The problem wasn't solved, meaning I don't think annealing had anything to do with the problem.

I've previously read AMP's write up on SBA. I suspect (though I'm not 100% certain) that they are saying SBA doesn't yield PERFECT results. Let's say that a perfect anneal would result in a hardness of 7 (made up measure). SBA might result in all my brass having a hardness of 6 (or 8) - not the perfect hardness, but a consistent one across all my brass. I'm ok with a consistent hardness, even if not the optimal hardness for longevity.

I've read that before induction annealing, brass manufacturers used SBA. I've also seen plenty of precision shooters swear by SBA.

Am I (and the precision shooters) wrong? I don't know. I'll probably switch to induction just because it is simpler - not because I don't trust SBA.
 
#20
I think AMPs data was more to the effect that you may be stress relieving with SBA, but not actually annealing at that temp/time.

I recently started annealing (annealeez) and had to work up new loads to get back to my new brass accuracy. Annealing changes the hardness and spring back on the necks which changes the neck tension. My node didn't move very far, but it was far enough that the old load was now outside of it. Food for thought.
 
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#22
prickett said:
As mentioned previously the accuracy problem started before I ever annealed. I tried annealing to solve the problem. The problem wasn't solved, meaning I don't think annealing had anything to do with the problem.
Click to expand...
Brass that’s been worked too much without annealing is under-annealed. So this problem would show up before annealing. And if SBA didn’t work you’d get no change.
 
#23
prickett said:
I don't see why it'd be any slower than induction annealing. You have a rack that holds a quantity of cases (50, 100, 500, ... whatever) and you dip for 5ish seconds. Dump those and repeat with new cases.
Click to expand...

And why would you do that when it’s easier to run cases through a series of torches on a conveyer. There is a video on YouTube showing how Norma cases are made. The machinery looks antiquated. They use broomhead shaped torch setup. It’s pretty neat.

If sba was ever used in manufacturing it must have been during cowboy and indian times.
 
#24
Per the original question... I think there is such a thing as brass getting old 'just from sitting' but it is not an over night process and it generally will result from improper storage where air and heat and humidity can have an influence on things. I'm pretty sure you can get certain types of 'corrosion' that will ultimately harm the metals if you let it happen.

But just for relatively modern brass that has been used rather recently I would lean to the direction that annealing isn't being done correctly. Maybe your temps are too low or you're not letting them marinate long enough (or both)? I most certainly don't know the answer but I would say to save a few cases (as many as you can) and try a new method of annealing and see if the problem persists or not.
 
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