My German friend taught me to harden firing pins so the rear part is hard, but the tip is spring hard. He heated the whole thing cherry red and guench in oil, polish bright and then the tricky part. He heated rear part to "straw", while "playing it in and out of the flame ( propane torch) while watching the color. The rear being heavier than the tip, heat would travel to the tip faster and when the tip turned blue, immediately back in the oil.
Mike

Last edited by Der Ami; 11/23/20 09:52 AM.