ANY ACTUAL TESTING on neck hardness before/after ss pin cleaning ?

[retired]

has anyone done actual testing ,like with a rockwell hardness tester, on case necks before and after
cleaning with ss pins ?
time the cases were in the pins? number/weight of pins(total), number of cases in the mix
looking for FACTS and DATA.

i have seen this proposed and discussed in the past, but i have been away for a couple of years and was wondering if it has ever been proven/dis-proven ?

 

[Davey Boy]

Look down at #7 it says it doesn't affect hardness.

https://www.ampannealing.com/articles/40/annealing-under-the-microscope/

 

[retired]

actually, they may have missed the inside of the neck, but the inside of the case
say no.

 

[Webster]

has anyone done actual testing ,like with a rockwell hardness tester, on case necks before and after
cleaning with ss pins ??

I have done microhardness testing on cross-sections of at least a thousand samples in my career. The below article doesn’t mention the cases being tumble polished, I assume they were not, no damage observed on the surface or body walls in cross-section images. I have examined cross-sections of many sand blasted soft steel samples and other materials. The work hardened depth is under 0.0001”. SS pins are impacting the brass with a very low amount of energy. Proof of this is there is no texture change on the surface. It looks like the pins are just removing the dirt and oxide layer.

https://www.ampannealing.com/articles/40/annealing-under-the-microscope/

The article does not have an image of a magnified cross-section of the neck end. Reloaders have commented the ends of the necks are dinged. Cannot comment on this. If I was still working I would examine a few case neck ends. Bottom line is that even if the surface was cold worked by SS pins the depth of damage would be to an insignificant depth and would not contribute to the total grip. If the SS pins impacted the case surface with enough energy to cold work the metal there would be at least microscopic size dents that you couldn’t see with your eye. Altogether they would contribute to a dulled surface finish. You have the opposite a polished surface.

I can hardly wait for responses to this.

 

[retired]

it is what i expected. after all we seat bullets on the inside of the neck.
thanks

I have done microhardness testing on cross-sections of at least a thousand samples in my career. The below article doesn’t mention the cases being tumble polished, I assume they were not, no damage observed on the surface or body walls in cross-section images. I have examined cross-sections of many sand blasted soft steel samples and other materials. The work hardened depth is under 0.0001”. SS pins are impacting the brass with a very low amount of energy. Proof of this is there is no texture change on the surface. It looks like the pins are just removing the dirt and oxide layer.

https://www.ampannealing.com/articles/40/annealing-under-the-microscope/

The article does not have an image of a magnified cross-section of the neck end. Reloaders have commented the ends of the necks are dinged. Cannot comment on this. If I was still working I would examine a few case neck ends. Bottom line is that even if the surface was cold worked by SS pins the depth of damage would be to an insignificant depth and would not contribute to the total grip. If the SS pins impacted the case surface with enough energy to cold work the metal there would be at least microscopic size dents that you couldn’t see with your eye. Altogether they would contribute to a dulled surface finish. You have the opposite a polished surface.

I can hardly wait for responses to this.

 

[dcali]

Work hardening means just that - you have to work the brass to harden it. AMP’s results are as expected. None of the brass is moving except the thinnest layer under the impact of the pins, which is probably moving quite a bit *as a percentage of its thickness* (the stress at the precise point of impact is pretty high, but dissipates quickly). This would explain a very thin hardening effect.

 

[Berger.Fan222]

Not set up for hardness testing, but my standard practice is to tumble 4-5 hours between firings.

I have Lapua .223 cases on their 13th firing with no neck splits without annealing (other than the original factory annealing), so I can't see any negative effects of tumbling on case life.

My experience has been that poor brass quality to start with (Fed, Rem, etc.), hot loads, and loose chambers rob much more case life than SS pin cleaning. I have yet to discern a single negative effect of SS pin cleaning.

 

[retired]

selective use of data. the very thin work hardened "skin" is MINOR compared to the overall CASE THICKNESS. to claim it is "moving quite a bit" is very selective use of a small part of the real picture.
the bottom line the exterior surface of the case just does not care.

Work hardening means just that - you have to work the brass to harden it. AMP’s results are as expected. None of the brass is moving except the thinnest layer under the impact of the pins, which is probably moving quite a bit *as a percentage of its thickness* (the stress at the precise point of impact is pretty high, but dissipates quickly). This would explain a very thin hardening effect.

 

[dcali]

*as a percentage of its thickness*

The very thin outer layer that *does* work harden *does* move a good deal *as a percentage of its thickness*, and is therefore work hardened.

 

[retired]

and has nothing to do with the usefulness or lack of usefulness of a ss pin cleaned case.
zzzzzzzzzzzzzzz

*as a percentage of its thickness*

The very thin outer layer that *does* work harden *does* move a good deal *as a percentage of its thickness*, and is therefore work hardened.

 

[Webster]

Work hardening means just that - you have to work the brass to harden it. AMP’s results are as expected. None of the brass is moving except the thinnest layer under the impact of the pins, which is probably moving quite a bit *as a percentage of its thickness* (the stress at the precise point of impact is pretty high, but dissipates quickly). This would explain a very thin hardening effect.

This is all made up assumptions. The cases and pins roll against each other surrounded by water. The impact is almost zero.

 

[retired]

no this was actual before and after testing paid for by AMP.
it is close to zero, no visual change, but measurable exterior surface change. in real life practical application no reloading ill affect.

This is all made up assumptions. The cases and pins roll against each other surrounded by water. The impact is almost zero.

 

[ireload2]

It matters little after you anneal the brass.
Sizing the neck and firing the cases also cold work the brass.
At some point the minutia has to be ignored.

 

[dcali]

This is all made up assumptions. The cases and pins roll against each other surrounded by water. The impact is almost zero.

Then how do you explain the surface hardening?

 

[Webster]

Then how do you explain the surface hardening?

No one ever said or proved surface hardening occurred. Some of these so called facts are made up by guys in there basement loading ammo. No hardness data exist that I know of to prove otherwise.

 

[retired]

you need to READ the AMP DATA/FACTS and quit passing around rumors.

No one ever said or proved surface hardening occurred. Some of these so called facts are made up by guys in there basement loading ammo. No hardness data exist that I know of to prove otherwise.

 

[jlow]

actually, they may have missed the inside of the neck, but the inside of the case
say no.

The inside of rifle case neck is the last possible place for work hardening by SS pins. Basically the dimensions of the pins makes it so that they can only travel by the surface of the neck in the horizontal position, making direct impact impossible.

 

[dcali]

No one ever said or proved surface hardening occurred. Some of these so called facts are made up by guys in there basement loading ammo. No hardness data exist that I know of to prove otherwise.

AMP said that testing the hardness of the neck while the case was on a mandrel showed hardening occurred. When they repeated the test on the cross section of the neck, they showed that the hardness was microscopically thin and confined to the outer surface. This is entirely consistent from some slight work hardening of the case exterior due to the impact of the pins. Any hard layer that thin is of no consequence to reloaders. But it's useful to know it's there because certain methods of hardness testing (that is, testing on the outer surface of the neck, which is the easiest and most obvious place to start) have now been reasonably shown to be inaccurate if you are tumbling in pins.

 

[Webster]

AMP said that testing the hardness of the neck while the case was on a mandrel showed hardening occurred. When they repeated the test on the cross section of the neck, they showed that the hardness was microscopically thin and confined to the outer surface. This is entirely consistent from some slight work hardening of the case exterior due to the impact of the pins. Any hard layer that thin is of no consequence to reloaders. But it's useful to know it's there because certain methods of hardness testing (that is, testing on the outer surface of the neck, which is the easiest and most obvious place to start) have now been reasonably shown to be inaccurate if you are tumbling in pins.

Did they say the case was pin polished. I have done microhardness for 45 years. It's impossible to get closer than several thousanths

The inside of rifle case neck is the last possible place for work hardening by SS pins. Basically the dimensions of the pins makes it so that they can only travel by the surface of the neck in the horizontal position, making direct impact impossible.

Good point the flat sides of the pins touch the cases not the ends.

 

[ballisticdaddy]

Just spin a case neck that has been tumbled with SS pins on your fingertip, what caused that?