I tested the annealing theory of holding the case in your fingers some time back. Using tempilaq I couldnt get the neck past 400 f before it became to hot to hold, this was on a 280ai case. So it wasnt achieving anything.
The candle theory was worse, all it did was cover the neck in soot and burn my fingers :D Iv also tested the base of all my cases with tempilaq on the base with a automated flame anneal er, with the necks indicating 750 F I been happy letting them cool at room temp for many years.
The case length gauge insert is an easy way to check for trim length. @
Tahr you are welcome to borrow this one in .284 if needed. Just trim the neck of a sized case back. Fit the insert then chamber, it will push the insert into the case indicating the max length, I normally trim 10-15 tho shorter.
Attachment 131611