Not sure about brass. But steel temperature is reliability judged by colour. I would have thought (given it is an alloy) temperature could be judged with some reliability.
There is a cost factor here. If I don’t anneal I’ll be throwing them away soon due to splits. If I anneal I should save most of them. The the choice is, save most or toss them all out! No brained to me.
Especially as it is the change from the original colour to something else. Wether it be pink or blue 
it that first sign of changing that indicates when it is done.
Only under specific conditions, OB. Colour perception is extremely variable according to light conditions. Steel temps can be guessed at but colour is not a good way to judge when temps are critical to outcomes, such as heat treating. You can get a result but it is not likely to be optimal nor reliably repeatable.
True, it’s not 100% but should be close enough. If it’s not, then I lose a few extra. So what.
There’s probably only one way to say this, with any civility.
There are three possible outcomes to this exacting process, if measured by you eyechrometer.
@oldAG I know nothing about annealing cases but i want to do it to the cases i’m making here
Making 12ga (almost) from hell brass
before I fireform them.
Can you talk me / us through how to do it properly?
I have been following this thread and I have watched a couple of (probably dodgy) YouTube vids but as these cases cost me a bit in both time and money I’d like to do it right.
You don’t need to do it right this second but since you seem to know whats what i’d love to get your take on it.
I am NOT saying it is a waste of time. Done properly it is very beneficial.
To do it properly, you have to understand how the grain structure of the brass is changed.
I used to have a two burner automated annealing machine, which still required setting up with temperature sensitive paint, the most commonly used one being Tempilaq. Welding supply shops will either have it or source it for you.
http://www.tempil.com/tempilaq-indicating-liquids/
I have moved on from that and now use an AMP induction heating annealer. I anneal a LOT of cases.
https://www.ampannealing.com/
Rather than me trying to talk/walk you through the process, I suggest you read the excellent article posted quite some time ago in the 6mmBR web site. It is written by Ken Light whose machine is shown in that article and is the type I used to have.
http://www.6mmbr.com/annealing.html
Please understand that it is a very exacting process, which is why I finally moved to the induction type. But, if you use the gas method correctly, your results will be just as good - it just takes longer in the setting up and, gas burners anywhere near a reloading workshop is not a sensible proposition.
I use tempilaq and a bench source annealer. Would love one of those AMP induction annealers
@oldAG I am going to make a backup copy of that page and try to collate a few things into ‘knowledge base’ post for articles section. Would be good if you (and @Gwion who seems to know what he’s on about) could post some tricks and tips beyond what’s here.
When i started I over annealed a few cases some by accident and some on purpose. To the point of bright orange / Red you could see the grain change a bit. However the temp at the middle and base of the case did not even reach the annealing temp. The cases were fine to use I may not have got the 1/4 MOA accuracy out of them but no splits or sticking either. A few uses later and they are probably getting hard again.
Thanks for that info @sungazer. Very usefull.
Perhaps to get it spot-on it’s difficult. But to get a practical improvement not so hard.
All i know is what I’ve read, so definitely no authority on annealing. Although, I have learned a few things about metal, heat and colour over the last few years through my interest in forging blades.
From experience, it is very difficult to get repeatable results by reading colour changes. Sure, you can tell when it is way too hot but when you are talking an effective window of maybe 50degC to do the job in seconds… good luck with that!
I guess if it is plinking ammo that you just want to last longer: go for it; as long as you don’t over heat the case body, which would be very bad. Worst is probably that it ends up too soft and collapses in your press. On the other hand, if you are annealing for a consistent neck tension in conjunction with neck turning and reaming, to squeeze the utmost precision out of your rounds for the pointy end of target shooting: at best you are just wasting your time unless you do it properly; at worst you are making things worse due to inconsistent properties of the case mouth.
Sooo, I had a crack tonight and annealed about 20 cases. Just used what I call a “Pencil tip” in an LPG torch and a piece of wooden dowel with a hole drilled in the end to hold and rotate the 30-06 cases. I used the table cloth in the pics for a light coloured back ground and a small lamp for light. (not quite as light as normal shed lights) Just rotated for about 9 seconds until the blue colour could be seen. then dumped them on a damp cloth. Obviously not all identical.
I just held the torch handle in a bench vice. (KISS) Once set up took no time at all. Not perfect but I think good enough to extend the life of the cases.
Here is a random sample.
And the torch I used.
Looks good, you will have to let us know how they go.
I have a LPG torch exactly the same with two or three different tips, but I am having a lot of trouble getting the correct flame from it. It must be very pressure sensitive.
Jet might need cleaning. Should be a blue flame.
@Oldbloke seen this on Facebook and thought that it might interest you. He is selling them at $400 a pop.
You can make one of them yourself if so inclined. Skips case annealer - black Betty. Was designed by a bloke called skip on the shooting Australia forum with input from a heap of other members. There are a number of YouTube vids from skip and others who’ve made them.
They would be great if you need to anneal 100s. But like many other shooters I only need to do perhaps 20 or 40 at a time. In fact to be real probably should just buy new cases. But I like tinkering and don’t like spending. 
