I just did my 300 win mag with propane torch, low intensity. approx 18-20 seconds per case, in a socket on a drill.
The gray is 1/4'' below shoulder.
Fine?
Unless you anneal the lower half of the case, I guess you cant really over anneal the neck unless you get it to glow red hot or something?
Result sounds like what you did is just fine but 18-20 sec hold on heat sounds weird.I think you might have used low flame.Try adjusting flame until it takes you only 5-7 sec of hold to get the same result.
vviking is right-practice on more common cases.Brass heats up very fast and you should minimize heat exposure of the rest of the case as much as possible.



















































