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Interesting points on annealing


Catch-22

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I know what you’re all thinking, “Uh oh, not ANOTHER thread about annealing”.

However, I came across a couple of really interesting videos by a chap who’s supposedly a metallurgist by trade and is a shooter. I found his vids to be very informative and explain the annealing process in greater detail than I’d read/heard before. 

I’ve been annealing for a while and, tbh, I just followed the crowd using tempilaq 750f on the inside of the necks to see when it’s at temp, thinking once the paint tells me it’s done then the brass is correctly annealed. I sort of felt that made sense, even though I didn’t fully understand the ‘how’ behind it - specifically how the 750f temp was derived and whether using tempilaq (or other) markers actually meant I was annealing correctly.

I used to gas anneal, now use a home made induction machine but the thing I’ve learnt most here is the use of such paints may actually mean you’re not getting a full proper anneal. The charts used to infer the 700-750f temp range, which we’ve all read and understand to be the correct annealing temp, actually state you require a 750f temperature over a 1hr period. Time is the crucial thing here. Obviously our cases would be ruined after 1hr as the case head would be affected.

His video explains we should reach a higher temp for a short time (eg 900-1000f for a few seconds) so it achieves the same equivalent annealing value of 750f over a 1hr period. 
His explanation and charts kinda made sense to me. At least I feel someone explained the mathematics/metallurgical thinking behind the rationale, as apposed to just someone on a forum saying ‘buy 750f tempilaq and you’re good’.

For me, I’m going to try some reloads using brass that’s been annealed at the 750f mark (per tempilaq indicators) and some annealed to the point where they just appear to turn a dark red in a darkened room (roughly 900-1000f). I want to see if there’s any noticeable change in ES/SD and group size between them.

Worth a watch and derive your own conclusions from.

Pt 1:

Pt 2:

 

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I have experimented with gas flame on a timed rotation platform and could see too much variability as setting the flame temperature is an educated guess especially as gas pressure drops due to expansion chilling in the bottle (yes I know this can be moderated).   Induction heating is good, provided that it's stable and timed accurately (I maintained huge 80kW Crossley RF induction sets back in the day so have some experience)

This is exactly why I went for salt bath annealing - I anneal at 510C (950F) for ~4 sec (dependant on case type etc)  The temperature of the bath is precisely controlled, the time is precisely controlled, the insertion depth is the same so the resultant heat input into the brass is close to identical for every case.  The time/heat gives me sufficient annealing at the right place in the curve without being too long and over annealing down the case.

The reason I don't go above 510C is the salt mix can start to fume and that's really bad 😟 

My real-world experience and results give me reason to continue.

 

 

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6 minutes ago, Popsbengo said:

I have experimented with gas flame on a timed rotation platform and could see too much variability as setting the flame temperature is an educated guess especially as gas pressure drops due to expansion chilling in the bottle (yes I know this can be moderated).   Induction heating is good, provided that it's stable and timed accurately (I maintained huge 80kW Crossley RF induction sets back in the day so have some experience)

This is exactly why I went for salt bath annealing - I anneal at 510C (950F) for ~4 sec (dependant on case type etc)  The temperature of the bath is precisely controlled, the time is precisely controlled, the insertion depth is the same so the resultant heat input into the brass is close to identical for every case.  The time/heat gives me sufficient annealing at the right place in the curve without being too long and over annealing down the case.

The reason I don't go above 510C is the salt mix can start to fume and that's really bad 😟 

My real-world experience and results give me reason to continue.

 

 

Yeah, it’s for those same reasons I went away from gas flame and switched to induction. Personally I didn’t fancy salt bath as I don’t have the dedicated space to have it setup the whole time, and felt it was perhaps a bit more risky than flame and induction.

That stuff aside, can I ask why, or what convinced, you chose to anneal at 950f for c. 4s? 
I think that’s the point made in the videos, that we should be reaching a higher temp than 750f for a short time if we want to achieve proper annealing.
Everything I’ve read (and practised myself) appears to be wrong; that by simply heating the case to around 750f (using whatever method you like, flame, induction, salt, voodoo...)it’s then annealed properly. Seems that the temp needs to be heated much higher, eg 900-1000f for a few seconds to be correctly annealed, not 750f for a few seconds. It’s this which has lead me to discount the paint indicators (unless perhaps using a 1000f paint??) and rather look for that dull glow (indicating the right temperature) and noting the short time it took to get there. Then repeat that CONSISTENTLY for all cases, time after time.

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I have been using the dull glow (cherry red) for quite a few years now, and I only look for it inside the neck, I find it is very repeatable once you know what to look for, you have to be very very vigilant as the case leaves the flame. This normally coincides with what I believe is called burn off and the flame changes colour. Years ago this was said to be to hot, but if you watch the Benchsource annealing video this is exactly what happens.

I did a test a few years ago with brass annealed at 3 different temperatures and tested I believe at 600 yards, the third set of cases I expect 99% of people would have said they were over annealed (if only I had made a video) I will have a search for it, although I was informed that my test groups of 5 shots for each temperature were not enough.

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45 minutes ago, John MH said:

Take the guess work out of it:
 

 

yes indeed!  Use a salt bath 😉😂

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1 hour ago, Catch-22 said:

That stuff aside, can I ask why, or what convinced, you chose to anneal at 950f for c. 4s? 
I think that’s the point made in the videos, that we should be reaching a higher temp than 750f for a short time if we want to achieve proper annealing.

By experimentation with scrap cases, I settled on 510C (950F for Yanks) for ~4sec as it gave the right time/temperature to achieve a decent annealing without overheating down the case  - I'd have tried hotter temps for less time except for the risk of fuming nitrates. 

Familiarity with the engineering techniques from my professional life helped me to avoid the bullcrap peddled on Youboob and advertising bullshine by others.

I did experiment with gas (as posted earlier) but it was apparent that it was too hit and miss and Tempilaq is a very crude method of setting up.  Very variable quality

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That’s interesting.

The chap follows up in some other very useful videos that his testing shows changes in SD/ES as well as case growth and neck diameter.

His findings, and that of the AMP team, found when the ideal anneal had been achieved, the case both grew in length and ES/SD lowered AFTER having passed beyond a sort of ‘hump’. He notes that as you heat the the brass up, so that it recrystallises before being fully annealed, you should be able to see your load ES/SD curve goes upward (bad) before then dropping back down again (good). He notes that velocity also increases, then decreases again to a plateau. 
So it appears there’s a correlation to improved SD/ES and increased case growth but not the top velocity, just a constant one.

So it seems to me that to determine if optimum annealing has indeed occurred, you need to test a bunch of  cases that have been annealed at different temps/times with whatever method you use, load and shoot and plot the ES/SD. Look for where your loads increase in velocity, then drop again, and you should see your ES/SD drop too. Thats when you know you’re annealed correctly.

Measuring colour change or what the tempilaq change isn’t good enough - it’s some trial and error and, more crucially, observing how your loads perform to determine correct annealing.

It’s the only way to be sure, unless of course you buy the AMP - they’ve done all that testing for you and measured the consistency of brass recrystallisation with the Vickers tests. But that’s why you pay the big $$$, for that legwork.

Again, I have no stake or background knowledge in metallurgy - but I have found the explanations and examples in these videos extremely helpful and to me they make a lot of sense. I for one have learnt some useful things and will definitely try various loads that have been annealed for varying temp/time before observing my ES/SD for that ‘drop off’ point.

Annealing ladder testing

Pt 1: 

Pt 2::


Pt 3:

 

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  • 2 weeks later...

I use tempilaq 750 in flame, it melts I dump the case in water, the case spins in a tool no longer marketed by Hornady. Works fine I saved hundreds of cases from cracking after the first lot of 400 40 or so split necks on first firing.  Could I make the process more complicated? Yes, will I? No.

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Oh dear, sadly it seems few people here have actually understood the point of this thread or watched the detailed videos.

If you’re heating your brass to 750f, like I used to, you’re doing it wrong. You’re not actually annealing your brass. Using tempilaq paint to tell you you’ve reached 750f then stopping the heat...is NOT correct. Your brass is NOT annealed properly.

The 750f temperature often talked about is only applicable if heating your brass at 750f...for 1hr!!!
But heating your brass for 1hr will ruin the brass.

To correctly anneal your brass, you need to be heating to around 950-1000f as quickly as possible, often just a second or two with an induction machine.

But to truly determine if you’ve annealed properly, you need to test them. 
Only when you see a lowering of your ES/SD and see your velocity increase, then decrease and plateau, confirms the annealing temperature + time is correct.

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Just now, Catch-22 said:

Oh dear, sadly it seems few people here have actually understood the point of this thread or watched the detailed videos.

If you’re heating your brass to 750f, like I used to, you’re doing it wrong. You’re not actually annealing your brass.

The 750f temperature often talked about is only applicable if heating your brass at 750f...for 1hr!!!
But heating your brass for 1hr will ruin the brass.

To correctly anneal your brass, you need to be heating to around 950-1000f as quickly as possible, often just a second or two with an induction machine.

But to truly determine if you’ve annealed properly, you need to test them. 
Only when you see a lowering of your ES/SD and see your velocity increase, then decrease and plateau, confirms the annealing temperature + time is correct.

I don't buy your last line; For sure annealing will assist in reducing ES by equalising neck tension but ES is also dependant on many other variables that must be managed.  Actually, if all the necks were equally hard then that would be a constant too - not conducive to long case life maybe, but equal.

With regard to "people doing it wrong" well, if they get case life and adequate accuracy I'd say carry on with what is working for them.  Empirical evidence rules !

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I don't bother with  tempilaq , I have a bottle somewhere . I like to heat using two burners until it just starts to glow dull red/flame changes colour and that's it done which I believe is around the 1K degrees mark .

I don't get split necks , brass lasts , easy to FL size , low single figure ES/SD  I don't know what else I could gain from changing what I do .

I will say although I personally do not rate  tempilaq for rifle brass , it does IMHO have a handy use for pistol or short case brass in general , my little .22 hornet and 44/40 being a prime examples  . I put a dab near base ( about 1/3 to 1/2 way ) just to make sure I'm not getting to much heat near the base . anyone who has tried will know that annealing pistol/short brass can have so very interesting results if rules are not followed 🙂

 

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I have a AMP Mk2 now but have had both a Bench-Source Vertex and much copied Giraud Tool Cartridge Case Annealer. Setting up both I used Tempilaq, 750F on the inside of case mouths and 350F on the outside from case head up to the neck. In the absence of a high tech method of measuring the temperature this the Tempilaq is probably the simplest way of getting a 'ball park' indication of the temperature being achieved. I also used to darken the room I was annealing in so that I could see the case neck start to just glow red, similar to how Eric C demonstrates. I had no problem with that method and do believe my cases were annealed as the 'feel' when seating bullets was consistent and 'smooth'. I would suggest that when the Tempilaq paint burns off you have achieved the minimum temperature on the bottle, ie to burn the 750F off you have reached at least 750F but probably a lot more, I think the 350F paint on the case wall is a better indicator that you have not overheated the neck as the heat travels so quickly through the brass. Been doing it that way since 2007 without any issues.

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As I turns out I will be doing some annealing tomorrow night and I will test what the actual temp of my cases using my vertex with my Fluke industrial laser thermometer. That’s goes upto 650 C / 1200 F . And before anyone asks yes it is certificated. 
edited to say as long as I can do it of course , I have never thought of trying this before as I just followed the instructions that came with my vertex and had no reason to doubt it . But we will see .

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4 hours ago, Popsbengo said:

I don't buy your last line; For sure annealing will assist in reducing ES by equalising neck tension but ES is also dependant on many other variables that must be managed.  Actually, if all the necks were equally hard then that would be a constant too - not conducive to long case life maybe, but equal.

With regard to "people doing it wrong" well, if they get case life and adequate accuracy I'd say carry on with what is working for them.  Empirical evidence rules !

Thats not what I’m saying. True that ES/SD is affected by a lot of different variables. 
But the point is that when annealing at different temperatures and for different lengths of time, given no other changes to your loads, the evidence from load testing should show changes in both velocity and ES/SD. As you get towards the optimum state of annealment (is that a word??) your loads should see increase in velocity then a drop off to a consistent plateau. Same for ES/SD. It’ll increase then suddenly start to drop.

Im not stating that by annealing alone you are able to significantly improve your ES/SD.

And if you watch the videos through, I think the evidence he puts forward with his testing provides the evidence you’re asking for 👍

And i for one will run my own tests, similar to him, where i incrementally increase the annealing time and test the loads made up and interrogate the data for where the optimum temperature + time sits for me.

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1 hour ago, One on top of two said:

As I turns out I will be doing some annealing tomorrow night and I will test what the actual temp of my cases using my vertex with my Fluke industrial laser thermometer. That’s goes upto 650 C / 1200 F . And before anyone asks yes it is certificated. 
edited to say as long as I can do it of course , I have never thought of trying this before as I just followed the instructions that came with my vertex and had no reason to doubt it . But we will see .

Would be interesting to see what the ‘peak’ temperature reached is.

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Well I have had a go and I just can’t get an accurate reading. The heat from the flame is giving me mixed readings and if I wait the case moves out of flames cools to quickly so gives me a false reading, if you know what I mean . 
it would have been nice to have some data , but I just can’t complain with the results I’m getting with the 4 seconds I’m currently giving my Peterson .308 brass .

so as they say ....... if ain’t broke..... 

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