Sorry to be that guy that brings up AMP, but I'm not here to say they're better, promise. To me the core of what their research showed (and why IMO their recommendation to use flame annealing as an alternative isn't just lip service) is because they're trying to work on consistency, never do they state that flame doesn't provide a similar "full anneal" like induction also does. Their own AZTEC codes vary somewhat but that's ok, because as you said it's a window, not a narrow specific point. They're saying that you get more consistent bump by getting to the full anneal point every time, and their marketing shtick is using induction ensures you get all the way there every time easier/faster/more consistently compared to alternatives.
Flame people in the hotter/redder crowd get there every time also. It's an easy process that people overcomplicate because unless you cook it to the point it crumples you're pretty much always fine with the neck. Enter the
@ButterBean YouTube video, because it really is that straightforward.
(Disclaimer: I voted for induction with my wallet, ultimately I felt like I needed to have an electric machine since I load in my house. Flame might be great but I moved out of my garage and into the AC for a reason. Texas is hot, y'all, and my wife would kill me for literally playing with fire in the house.)
AMP counters salt bath annealing by stating it's partial and not complete by their standards. But to several people here that's the point of using salt bath - to not get to a completely annealed state. So each process works by different standards, because the end goal is a pretty wide range.
At the end of the day if the case head is fine, the case should still be useable.
Vermilion maybe? Scarlet seems a bit bright. Try printing out a color chart and holding it next to the case as you heat it. I use the 3AAA battery LED headlamp from Creedmoor Sports (a bargain at $49.95) that has a neutral 5k white tone and a calibrated red chart to confirm the exact timing in the flame:
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