I have to form brass for my .33WCF 1886 Winchester from .45-70 brass using a .40-60 sizing die as an intermediate stage.

I anneal before each step, holding the case rims in my bare fingers while rotating the neck in a gas flame.

The need to let go of the rim when it starts to become uncomfortable, dropping the case into a water bucket, avoids any risk of over heating and softening of the case head.

It may not be very precise, but the annealing colours usually extend to just below the case shoulder.