By hard steel do you mean tool steel. If you do and it's heat treated, it could crack under heavy stress. Do you have access to Impax tool steel. This would work good if it wasn't heat treated. Otherwise, I would just use a mild steel. When you make these, (or have them made) make more than one. Because if your turning the steel and drilling it, it just takes a few more seconds to machine more than one length. This will give you a spare if/when you need it.