I'd go with mild steel, casehardened. It is easy to work, yet can be hardened where you need it with a casehardening, tempered back in areas that need toughness and wear resistance, such as pivot holes and striker bars, tempered back to spring hardness for the finger levers. Leave the trip edges very hard. Casehardening gives one a lot of control.
As Dan says, high carb or 0-1 toolsteel can be a little less forgiving when the parts are subjected to impact. A more careful hardening and tempering is required.