Salt bath annealing
- Thread starter TrxR
- Start date
Below testing Peterson neck tension without annealing, the green bars is neck tension and remains very constant without annealing after ten sizings and firings.
What happens to Case Neck Tension after repeated firings?
https://www.petersoncartridge.com/technical-articles/posts/2018/january/what-happens-to-case-neck-tension-after-repeated-firings/
Do you think neck tension on brass rifle casings increases or decreases with continued firings from the same casing?
At Peterson Cartridge, many of our customers are long-distance, competition shooters who reload and re-shoot our casings over and over again. Neck tension is one of the variables in the formula for winning performance. And all the variables matter to these shooters. In an effort to continue being a valuable resource to these shooters, we set out to answer the question, “What happens to Case Neck Tension after repeated firings?” And, “Does that have any influence over velocity?
”I presumed neck tension would lessen with repeated firings. I supposed that the more times a case was fired the looser the mouth would get… I was wrong.
At Peterson Cartridge we had an instrument maker custom build a casing neck tension measuring instrument for us. It inserts a mandrel the exact size of a bullet into the mouth of a casing. It measures the force in pounds to insert the bullet and to extract it. The insertion and extraction motions are driven by a motor. (With other less expensive instruments the motion is driven by a hand crank. But results from those can vary depending on the vigor of the person running the crank.)
We asked our ballistician to take some of our .308 Win Match casings and fire them 10 times. After each firing he resized the neck. Then he measured the neck tension. Then he had to resize the neck again because inserting the mandrel would have changed the neck. Then he reloaded and fired, and repeated the process nine more times.
The neck tension results are produced on a computer screen, as shown below:
What happens to Case Neck Tension after repeated firings?
https://www.petersoncartridge.com/technical-articles/posts/2018/january/what-happens-to-case-neck-tension-after-repeated-firings/
Do you think neck tension on brass rifle casings increases or decreases with continued firings from the same casing?
At Peterson Cartridge, many of our customers are long-distance, competition shooters who reload and re-shoot our casings over and over again. Neck tension is one of the variables in the formula for winning performance. And all the variables matter to these shooters. In an effort to continue being a valuable resource to these shooters, we set out to answer the question, “What happens to Case Neck Tension after repeated firings?” And, “Does that have any influence over velocity?
”I presumed neck tension would lessen with repeated firings. I supposed that the more times a case was fired the looser the mouth would get… I was wrong.
At Peterson Cartridge we had an instrument maker custom build a casing neck tension measuring instrument for us. It inserts a mandrel the exact size of a bullet into the mouth of a casing. It measures the force in pounds to insert the bullet and to extract it. The insertion and extraction motions are driven by a motor. (With other less expensive instruments the motion is driven by a hand crank. But results from those can vary depending on the vigor of the person running the crank.)
We asked our ballistician to take some of our .308 Win Match casings and fire them 10 times. After each firing he resized the neck. Then he measured the neck tension. Then he had to resize the neck again because inserting the mandrel would have changed the neck. Then he reloaded and fired, and repeated the process nine more times.
The neck tension results are produced on a computer screen, as shown below:
:
Would be interesting to see results of the same test but with annealing after each firing.
If I had to guess, I would say the quenching is what is keeping the neck hard in AMP's test.
When I want to harden some carbon steel, I heat it, and quench it in oil. I would want to go back to my metallurgy textbook to confirm, but that's my initial suspicion.
To touch on Peterson's graph, David Tubb is on record insisting he does NOT anneal his brass. Maybe some food for thought.
When I want to harden some carbon steel, I heat it, and quench it in oil. I would want to go back to my metallurgy textbook to confirm, but that's my initial suspicion.
To touch on Peterson's graph, David Tubb is on record insisting he does NOT anneal his brass. Maybe some food for thought.
Last edited:
This is correct. Immersing in water is to stop heat migrating to the base and to rinse off thr salt
Copper and Copper alloys [brass, bronze] do NOT harden on quenching.
In fact, whether you quench or not makes a very minor difference for brass cases.
The case for quenching is to prevent the annealing from migrating to far
down the sidewalls of the case. D.
In fact, whether you quench or not makes a very minor difference for brass cases.
The case for quenching is to prevent the annealing from migrating to far
down the sidewalls of the case. D.
"Annealing Non-Ferrous Material: Almost all non-ferrous metals are
annealed by heating to somewhere just below the melting point and
then cooling in air or by quenching in water. Quenching in water is a
convenience.
Alpha brasses (64-99% copper) are annealed by heating to 700 to 1400
F (the hotter the softer) and can then be be quenched.
Alpha-beta brasses (55 to 64% copper) are annealed at the same
temperature and can hardened slightly by quenching from the
annealing temperature.
The key word above is slightly. Cold working produces a much greater
degree of hardness. The amount of hardening is so low my copper
alloys book does not give specific data. If quenched from the low end
of the annealing temperature there would be no discernable
difference."
annealed by heating to somewhere just below the melting point and
then cooling in air or by quenching in water. Quenching in water is a
convenience.
Alpha brasses (64-99% copper) are annealed by heating to 700 to 1400
F (the hotter the softer) and can then be be quenched.
Alpha-beta brasses (55 to 64% copper) are annealed at the same
temperature and can hardened slightly by quenching from the
annealing temperature.
The key word above is slightly. Cold working produces a much greater
degree of hardness. The amount of hardening is so low my copper
alloys book does not give specific data. If quenched from the low end
of the annealing temperature there would be no discernable
difference."
Below testing Peterson neck tension without annealing, the green bars is neck tension and remains very constant without annealing after ten sizings and firings.
What happens to Case Neck Tension after repeated firings?
https://www.petersoncartridge.com/t...-to-case-neck-tension-after-repeated-firings/
Do you think neck tension on brass rifle casings increases or decreases with continued firings from the same casing?
At Peterson Cartridge, many of our customers are long-distance, competition shooters who reload and re-shoot our casings over and over again. Neck tension is one of the variables in the formula for winning performance. And all the variables matter to these shooters. In an effort to continue being a valuable resource to these shooters, we set out to answer the question, “What happens to Case Neck Tension after repeated firings?” And, “Does that have any influence over velocity?
”I presumed neck tension would lessen with repeated firings. I supposed that the more times a case was fired the looser the mouth would get… I was wrong.
At Peterson Cartridge we had an instrument maker custom build a casing neck tension measuring instrument for us. It inserts a mandrel the exact size of a bullet into the mouth of a casing. It measures the force in pounds to insert the bullet and to extract it. The insertion and extraction motions are driven by a motor. (With other less expensive instruments the motion is driven by a hand crank. But results from those can vary depending on the vigor of the person running the crank.)
We asked our ballistician to take some of our .308 Win Match casings and fire them 10 times. After each firing he resized the neck. Then he measured the neck tension. Then he had to resize the neck again because inserting the mandrel would have changed the neck. Then he reloaded and fired, and repeated the process nine more times.
The neck tension results are produced on a computer screen, as shown below:
Hi Ed,
The green bars do not plot neck tension. They indicate the velocity attained by the bullet at a X10 plot. In other words, it looks like they plot at halfway between 250 and 300 or 275, which represent a velocity of 275 x 10 or around 2750fps. When you plot results like this it kind of 'wipes out' the details of the velocity but overall it seems to indicate that the velocity doesn't change much from firing #1 to reload and firing #10 without annealing.
On the other hand the graph indicates that there is a slow increase in neck tension from firing #1 through firing #4 and then a bit of a plateau (flat spot) from #4 to #10 with a bit of an outlier at reload #9. Still, if velocity is affected by the change in neck tension from around 100 pounds at load 0 to around 150 pounds at reload #4, there is nothing that would indicate it in the attained velocity data. In other words, this data shows that annealing appears to perform no useful benefit other than possibly to make it easier to seat a bullet!
