For the ones that do the salt bath annealing, how do you determine how long to keep your cartridge in the salt for the right amount of annealing?
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Salt Bath Annealing
- Thread starter jaybigboy34
- Start date
Experiment to see what gives you the best results. Should be 4-6 seconds or so from all of the results Ive seen on the web with the solution at 900 degrees or so.
It's a potassium nitrite and sodium nitrite blend made for annealing. I got mine from Ballistic Recreations (http://ballisticrecreations.ca/salt_home/salt-rev/) when I ordered their kit, but they're based in Canada so shipping will bite you in the ass. I'd look elsewhere for it or something similar.
Just ordered. Shipping at moment. I have 500ish pieces for a single sit test drive. Going to do a scientific drink beer and anneal session. I'll shit out my Harvad PHD science after.
Large batches is the best way to do it in my opinion. I sat down and trialed it with 50 pieces and it took almost no time. I'm pretty sure it took longer to set it up and put it away (melt the salt and wait for the salt to cool) than it did to do 50 pieces. In the future I'll be holding off until I have 200+ to do at once.
Not sure I'd have any other liquid around a molten pot of salt...asking for trouble.
You are correct. Beverage will be behind me. Should have mentioned that. Definitely not something to fuck around with.
Its "labor intensive" I guess and something that requires 100% attention and commitment(for potential saftey reasons). My kit from Canada is a route and I will do a test hopefully this weekend of 500+ (308)pieces in one setting for a test. And I need it done. I will be using my SS to assist and learn also. I'll post up after. I literally put money saved into finishing off a AR build.
That's pretty much it. I personally think that it's more consistent than anything propane based as well.
I think salt bath has the potential to be more consistent than propane-fired annealing, so long as the method used to keep each piece of brass in the salt for the same amount of time is consistent.
My Giraud annealer was definitely inconsistent over hundreds of pieces of .223 with a 1lb bottle, until I put a regulator on the propane line. I now check every ~150 pieces of brass with a Tempilaq'd case and my last annealing session showed the Tempilaq melting at the same point from the pieces used for initial set up all the way to the last test case done at the 1,100-1,200 mark.
I realize there are ways to keep the salt in a narrow temperature band, but other than a metronome or some other audible timer, how are folks ensuring each piece of brass stays in salt the for the same amount of time? I haven't done a ton of research into salt bath annealing, but there dosen't seem to be an automated way to dunk and retrieve the brass which would eliminate the human factor.
Some friends and I were discussing this yesterday on the side lines of a match and while we all thought SB annealing makes a bunch of sense, I couldn't get over the idea of sitting there and hand dunking every case. I know my mind would start to wander on such a mundane task and some sort of case feeding/lowering/raising/discarding mechanism would seem to be the ticket for large runs of brass.
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First I have heard of this but it reminds me of how Springfield Armory lead annealed the heels of M1 Garand receivers when they found some of them cracking under grenade blank useage.
Liguid metal annealing worked great in ensuring the first few years of Garand production did not require scrapping at a critical time of need.
With the fire, heat, attention required, lack of critical need......
sounds like SB annealing was created to sell AMP machines.
Liguid metal annealing worked great in ensuring the first few years of Garand production did not require scrapping at a critical time of need.
With the fire, heat, attention required, lack of critical need......
sounds like SB annealing was created to sell AMP machines.
Well, people "hand dunk" every piece of brass on an AMP, right? I get that the machine controls the annealing and you can let your mind wander a little more, but still, that's a very sought after annealing method.
In terms of automation, it could be done by something along the lines of the AMP autofeeder prototype, shown here: , but that would increase overall cost and the main reason I looked at SB was entry cost. Personally, I use a metronome and do a single case at a time. I'm not comfortable enough to alternate cases yet and it allows me to keep better track of the submersion time.
Annealing is very temperature sensitive but not very time sensitive.
Timing is critical when annealing brass using torches because the flame temperature is way higher than the temperature that you need the brass to reach. Leave the brass in for a few seconds too long and it's toast.
Time isn't as critical in salt bath annealing because brass will normalize and reach temperature equilibrium with the salt. You can't overheat the brass. Obviously you don't want to leave the case in the salt for an excessive amount of time, for then you will anneal the entire case as heat migrates from the neck up to the base.
The minimum time that brass is exposed to the salt is much more important. Pull out too soon and you haven't softened the metal enough. Leave it in a second or two too long, no big deal.
Timing is critical when annealing brass using torches because the flame temperature is way higher than the temperature that you need the brass to reach. Leave the brass in for a few seconds too long and it's toast.
Time isn't as critical in salt bath annealing because brass will normalize and reach temperature equilibrium with the salt. You can't overheat the brass. Obviously you don't want to leave the case in the salt for an excessive amount of time, for then you will anneal the entire case as heat migrates from the neck up to the base.
The minimum time that brass is exposed to the salt is much more important. Pull out too soon and you haven't softened the metal enough. Leave it in a second or two too long, no big deal.
Good point on the AMP requiring (at this point) to be single fed every piece of brass.
I guess it all comes down to the volume of cases being annealed.
I anneal in batches and when doing 1,000+ pieces of brass I'd go nuts feeding each one by hand and would certainly get a less consistent product if the only thing ensuring the heat was applied for a set amount of time was the gray matter between my ears.
Looks like salt bath, at this point, is great for low volume uses. Though I suspect as it gains popularity someone will 3D print a system which allows a user to remove themselves from the temporal aspect of this and just load cases into a hopper or feed chute of some kind before they are carried to, through, and out of the molten salt. Maybe a track above the salt with a chain which runs above; case rim rides in the track, a bend in the track takes the case down and then up, speed of the track is used to increase/decrease time in the salt?
In my mind's eye it looks like an erector set built over a salt pot, haha, but I'm sure others have thought of and/or already tried it, so who knows.
I guess it all comes down to the volume of cases being annealed.
I anneal in batches and when doing 1,000+ pieces of brass I'd go nuts feeding each one by hand and would certainly get a less consistent product if the only thing ensuring the heat was applied for a set amount of time was the gray matter between my ears.
Looks like salt bath, at this point, is great for low volume uses. Though I suspect as it gains popularity someone will 3D print a system which allows a user to remove themselves from the temporal aspect of this and just load cases into a hopper or feed chute of some kind before they are carried to, through, and out of the molten salt. Maybe a track above the salt with a chain which runs above; case rim rides in the track, a bend in the track takes the case down and then up, speed of the track is used to increase/decrease time in the salt?
In my mind's eye it looks like an erector set built over a salt pot, haha, but I'm sure others have thought of and/or already tried it, so who knows.
Pulling it out too soon and leaving it in too long certainly has its consequences......
I thought I said so.
The point is that salt bath annealing is MUCH more forgiving of timing inconsistencies compared to torch annealing.
It may be more forgiving in that it's harder to cook the case head on a piece of brass with the salt bath method, but does the reduction in consistency from case to case have a negative impact on the final product(s)?
By that I mean, will a case which was kept in long enough to get the benefits of having its grain restructured by the application of heat end up with the same grain structure as a case which was left in a couple seconds longer? While the above statement that the case kept in for a couple extra seconds won't be damaged or need to be tossed, did we create a consistent end result as far as the case mouth and neck are concerned?
I'm getting way outside of my knowledge base on this one, so I guess a better question to ask is if brass anneals in phases (750-800F are all similar, 800-850F are similar, etc), or does each additional degree of heat the brass raises lead to a different end product?
Doing a little research right now lead me to this article: https://bisonballistics.com/articles/the-science-of-cartridge-brass-annealing
The part that I think answers my question is: For cartridge brass, the transformation is rapid, robust, and occurs at approximately 650-700 degrees Fahrenheit. If you apply a higher temperature, the brass will get even softer, but not dramatically so.
If that is the case, and an increase in brass temp leads to a softer case, but not dramatically so, then the second piece mentioned above, the one which was left in the molten salt for a couple extra seconds, will not end up having a wildly different grain structure compared to the first piece, which was taken up to the required temp but then promptly removed.
I'm not trying to push folks one way or the other or argue for or against salt or propane or AMP; honestly trying to gain some knowledge as the science of annealing, and the real world positive impacts, are really interesting to me.
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Your link leads right back to this thread. I'd be interested in reading the article you quote.
I also think that many of the things reloaders obsess about are not as critical as one might think.
But the bottom line is this: without checking brass hardness, anything that you infer from the amount of time the metal is exposed to the heat source is at best an educated guess.
But that's the thing, you cannot get any one piece of brass hotter than another if they're all brought up to the temperature of the salt bath. Because of how heat transfer works, I cannot cook a piece to over 500 degrees Celsius in my pot. It's just that leaving it in too long will allow heat to migrate up the case into the head, which is not what we want.
I dont know how negligent you have to be with your application of heat but I have seen posts of people asking "What is wrong with my rounds?" than they show a picture of a brass case that they tried to seat a projectile in and the brass case is so soft that it pushes the neck back into the body of the cartridge and provides you with what looks like a sabot round.
I think that is the extreme.
I am just an enthusiast shooter.
My annealing concerns are more inclined to my cheapness and wanting to get a few extra loadings out of my brass.
Currently I send my brass off after three loadings to have someone else do it probably on a propane system.
I put my faith in the quality control of some anonymous person on the net. I hope they always get it right, so far I have realized positive benefits. So far they have gotten it right but I am in need of another means because my chosen annealers use of stainless steel pins to clean my brass absolutely makes the sizing portion of my progressive reloading a chore due to the carbon removal at the necks. If I use him again Ill ask for corn cob only prior to anneal.
Im reaching the point though that my cost in outsourcing is probably going to reach the level I could have bought equipment to do it myself. As an aside I loathe the thought of trying to place another piece of gear on my bench and the chamfer, debur, primer pocket cleaning of each individual piece of brass makes me want to quit reloading - would the individual handling of each piece of brass for the AMP make me consider same?
How much impact on target does a few miliseconds of annealing actually have?
Im guessing if it really makes that much difference to you, you have exceedingly great skills and you should probably use Lapua brass after one fire forming and you toss it for new fire formed cases after you use it once.
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And this is a downside to "un-scientific" annealing. Most of us don't have the resources to tell if we're actually doing it correctly. It poses the same problem in propane systems. We base our process off temperature because that is what causes the brass structure to change, not time (in our case). I think temperature acheives a level of consistency that would satisfy most shooters.
I agree. And even though I could bring an annealed case to work and check it on a hardness tester, I don't bother because it's just another variable that isn't THAT critical.
As long as some ductility is regained, load and shoot.
Something just dawned on me.
First thing to realize - annealing is about economically reloading not accuracy.
If accuracy is concern my example of the fire formed, neck sized custom high dollar brass is your method.
Annealing is about trying to get extra useage out of a work hardened peice of brass and squeeeze a few more uses out of it creating a cost savings.
If you are considering annealing as a means to get better accuracy than you are considering it for the wrong reason.
Its a cost savings first with the desire to restore some consistency in neck tension to a piece of over worked brass.
If accuracy is your main concern, costs being only secondary, go Lapua fire formed and neck sized.
How much do you value absolute accuracy potential?
First thing to realize - annealing is about economically reloading not accuracy.
If accuracy is concern my example of the fire formed, neck sized custom high dollar brass is your method.
Annealing is about trying to get extra useage out of a work hardened peice of brass and squeeeze a few more uses out of it creating a cost savings.
If you are considering annealing as a means to get better accuracy than you are considering it for the wrong reason.
Its a cost savings first with the desire to restore some consistency in neck tension to a piece of over worked brass.
If accuracy is your main concern, costs being only secondary, go Lapua fire formed and neck sized.
How much do you value absolute accuracy potential?
Whoops, let's try that again. Edited the post as well: https://bisonballistics.com/articles/the-science-of-cartridge-brass-annealing
Totally agree with aneeling being a bit of a dark art for the casual reloader who does it, but doesn't have the equipment to do actual hardness testing of the brass before and after.
My test results showed once fired LC had a lower SD if I annealed before resizing and doing the rest of my brass prep. Accuracy remained the same at 100yds, but the velocity spread made it a more consistent load for long range work.
Not true, annealing does improve accuracy. In my experience resized brass that has been annealed gives you more consistent
results. When I bump the shoulders back of annealed cases and cases that have not been annealed I find less variation in the datum length of the annealed cases. The annealed cases spring back more consistantly than non annealed cases.
The same applies with the case necks which affects bullet tension. The more consistent the ammo the more accurate it is.
But do you anneal virgin brass?
What is more consistent
a) "Virgin brass" that is only fire formed and neck sized
b) Multiple fired brass that requires annealing to prevent work hardening and as a means to restore ductility for a consistent neck tension.
A serious question.......I dont know a true answer, only speculating.
If money were no concern and you had a choice between using either of the two which do you choose?
I can't speak for whatsupdoc, but I anneal my brass destined for accuracy work every time so I can (try to) work with the same variables every loading.
I even anneal once fired LC that I purchase and use for DMR matches as I can actually feel the difference in the press when resizing. Once fired that isn't annealed is all over the place in the amount of force it takes to resize while the annealed brass feels more consistent from piece to piece. I believe this resetting of the grain structure of the brass is what leads to more consistent neck tension across the pieces of brass, which leads to my lowered SD.
Saving rare/expensive brass from the scrap heap with cracked necks is all well and good, but I do it in order to maintain as much consistency as possible across multiple reloads on the same brass and to attempt to set a baseline on brass which was not purchased and fire formed from a virgin state in my rifles.
Could still be throwing chicken bones in a corner with my limited findings, but I guess I'm willing to do it because I have an automated Giraud that'll get through a bunch of brass quickly
I can't speak for whatsupdoc, but I anneal my brass destined for accuracy work every time so I can (try to) work with the same variables every loading.
I even anneal once fired LC that I purchase and use for DMR matches as I can actually feel the difference in the press when resizing. Once fired that isn't annealed is all over the place in the amount of force it takes to resize while the annealed brass feels more consistent from piece to piece. I believe this resetting of the grain structure of the brass is what leads to more consistent neck tension across the pieces of brass, which leads to my lowered SD.
Saving rare/expensive brass from the scrap heap with cracked necks is all well and good, but I do it in order to maintain as much consistency as possible across multiple reloads on the same brass and to attempt to set a baseline on brass which was not purchased and fire formed from a virgin state in my rifles.
Could still be throwing chicken bones in a corner with my limited findings, but I guess I'm willing to do it because I have an automated Giraud that'll get through a bunch of brass quickly
Why not anneal for both? Extra brass life is great and consistency is something we all chase in reloading. I know I anneal to get a little of both.
But do you anneal virgin brass? Yes, and I also mandrel size the necks.
What is more consistent
a) "Virgin brass" that is only fire formed and neck sized Virgin brass and fire formed are two independent things. Cant be both.
b) Multiple fired brass that requires annealing to prevent work hardening and as a means to restore ductility for a consistent neck tension. Yes. And this is fire formed, its taking on the actual shape of the chamber.
A serious question.......I dont know a true answer, only speculating.
If money were no concern and you had a choice between using either of the two which do you choose? Fireformed brass that has been annealed to reduce the stresses in the brass. And if money were no concern I would just get a giruad to automate my annie annealer.
Cant argue against that.
I guess it comes down to what gives you the most mojo.
Scientifically though what is more consistent.
Fire formed to your chamber 1X neck sized Lapua
or third firing, annealed, neck sized Lapua?
Or should it be fire formed 1X, annealed, neck sized Lapua is the most consistent?
Thats why I put "Virgin Brass" in quotes.
Like a girl from Lynn, MA this is no such thing as "virgin" in the case of brass when "fire formed".
Third firing, annealed, full length sized. By three firings with a neck sizing only youre going to be prone to bolt click.
("Full length sizing" is not the exact same as "full length sizing to saami minimum specs". Only full length size enough to remove mechanical interference between the brass and the chamber, .02" of shoulder set back typically)
Each time you fire that case you are imparting the memory of the chamber on it, the more closely it will remember and retain that shape. After successive firings it will be getting work hardened and some stresses built up in the grain structure of the brass. Annealing reduces those stresses so as a result you not only get brass that becomes very consistent with your chamber but you are also getting brass that will continue to be easily formable with out any induced stress.
A graph courtesy of AMPs studies- notice the consistency of the brass at different ends of their life spans. I wish they would have included a line for the virgin brass. Though its not so much the hardness difference necessarily but the dimensional difference in virgin to fire formed that is the issue.
At least here they show the comparison.
("Full length sizing" is not the exact same as "full length sizing to saami minimum specs". Only full length size enough to remove mechanical interference between the brass and the chamber, .02" of shoulder set back typically)
Each time you fire that case you are imparting the memory of the chamber on it, the more closely it will remember and retain that shape. After successive firings it will be getting work hardened and some stresses built up in the grain structure of the brass. Annealing reduces those stresses so as a result you not only get brass that becomes very consistent with your chamber but you are also getting brass that will continue to be easily formable with out any induced stress.
A graph courtesy of AMPs studies- notice the consistency of the brass at different ends of their life spans. I wish they would have included a line for the virgin brass. Though its not so much the hardness difference necessarily but the dimensional difference in virgin to fire formed that is the issue.
At least here they show the comparison.
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I anneal every firing, virgin included, since that's what I'll be doing on firing 2 and beyond.
Third firing, annealed, full length sized. By three firings with a neck sizing only youre going to be prone to bolt click.
("Full length sizing" is not the exact same as "full length sizing to saami minimum specs". Only full length size enough to remove mechanical interference between the brass and the chamber, .02" of shoulder set back typically)
Each time you fire that case you are imparting the memory of the chamber on it, the more closely it will remember and retain that shape. After successive firings it will be getting work hardened and some stresses built up in the grain structure of the brass. Annealing reduces those stresses so as a result you not only get brass that becomes very consistent with your chamber but you are also getting brass that will continue to be easily formable with out any induced stress.
A graph courtesy of AMPs studies- notice the consistency of the brass at different ends of their life spans. I wish they would have included a line for the virgin brass. Though its not so much the hardness difference necessarily but the dimensional difference in virgin to fire formed that is the issue.
At least here they show the comparison.
There is some science.
I do not anneal virgin brass, In my opinion until it is fired and expanded in a particular chamber it is not ready for any high accuracy work.
I do anneal after every firing before sizing.
Another thing I forgot to mention in my previous post is bullet seating, my bullet seating consistency CBTO length improved by annealing the brass.
I do anneal after every firing before sizing.
Another thing I forgot to mention in my previous post is bullet seating, my bullet seating consistency CBTO length improved by annealing the brass.
I should have clarified; I anneal virgin brass if I'm going to be doing any sizing to it to increase or decrease neck tension, based on comparing measurements of empty brass and loaded dummy rounds.
My last batch of 6.5x47L brass gave me .002" neck tension out of the box, so I didn't anneal or size it, but my 338LM brass is going to be resized as it's giving .004" neck tension as it sits and I plan to open that up a couple thousandths and would like to avoid springback if at all possible.
Have a link to those tests?
Only have my anecdotal SD comparison data (with an N of 1) to go off of, so I'm definitely open to reading info from others who are smarter than myself on the subject.
