use map gas, it will be much quicker that using your mums stove to heat it up lol.
It needs to get cherry red to make any difference.
a tool post grinder will be a lot better and you can get much higher tolerances than normal turning, and a much better Finnish as well.
However, even if you use a tool post grinder you may still need to anneal the screw because where you turn the thread into the screw may still be in the hard or just on the edge where it goes soft, and this can be a bugger to put a thread for the locking nut if it is not totally soft.