Im in the planning stages of building a steel target for .22 rimfire . it will be a plate rack with 6 to 10, 2 inch round targets. The 2inch round is 3/8 thick Ar500 steel and the pivot arm will be a mild steel 3/8 thick x 1inch wide. My question is, Is there anything special I should know about welding a hardend and tempered steel to a mild steel?

I have access to several mig and stick welders and in pretty good at both. Any suggestions on what electrode or wire and gas. I think my friends gas in his MM252 is 75/25.

Frank aka The Weekend Welder