O’Grady, also a semi-finalist last year, knocked out world No 3 Rebecca McGinley in the quarter-finals with a drive of 302 yards – her first time over the 300 mark.
In the following round she hit another 300-yard drive, but was beaten by 14-year-old Elle Gibson (Shire).
“I’ve actually hit over 300 yards for the first time – and I did it twice,” said O’Grady. “I can’t ask for much more.”
Top qualifier Illona Stubley, from Glasgow, won the final against Gibson with a 307-yard hit.