Use "Drill Rod" it is usually sold in its annealed state. If you have a standard diy electric hand drill hold a length rod in the chuck to make a complete striker, turn the drill on and using a fine file turn down the rod to the longest length and diameter of your striker then polish with wet/dry paper. Reverse the rod so the longest length is held in the chuck and complete and polish the rest of the striker profile. The Drill Rod in its workable state is hard but wont last that long as a striker I usually heat strikers to red hot quench in oil re- polish and temper to purple, this gives the metal some spring resilience and lasting power
