Get some 750 tempilaq and a bottle of thinner. Once the tempilaq gets almost empty it’ll have started to dry out a bit with lots of goopy dry stuff so just pour some thinner in and shake it up and it’ll redissolve some of that build up, it’ll last a long time like that.
Put a thin layer of tempilaq on the outside of 10 case necks and let it dry until it’s powdery looking.
Grab some scrap brass to run 10-20 cases through to make sure it’s hot.
I don’t have the water coil but with the normal depending on how deep you position the neck and shoulder in the gap will vary how much energy goes into each and thus how soon or late each will heat with respect to each other. I like to keep it around the shoulder-body to mid shoulder in the middle so that a bit more energy goes into the shoulder which has more material. That’s in an effort to have the neck and shoulder turn the temp close to each other.
And then start with a creed case at 2 seconds and see what you get. Then 2.2. Then 2.4. At some point when the tempilaq starts to go clear (and then black if you keep cooking it) you will know you hit your temp, I go until it just gets started down the body a smidge. Do a couple more to verify and you’re done. The necks will always go before the shoulder though, can’t help it but that’s alright.
Steel wool 0000 will help you clean the tempilaq off those cases, scraping with another cases rim helps too.
In between these two examples with the green arrows that were .2 seconds apart is where I would try to set it at.
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There is a non lacquered example case next to each to show that you can’t tell on bare color alone.