Didn't he also hit a six iron?
"But when the work was finished, Shepard pulled out two golf balls and unfolded a collapsible golf club specially made for the occasion. Despite thick gloves and a stiff suit that forced him to swing the club with one hand only, he became the first ever to hit golf shots on the moon."
So far this is all I've found.
"Shepard produced a makeshift six-iron and two balls, which he whacked successfully."
You are correct.
He should hit a one iron so he can at least say he hit the club good once.