...since Hodgdon only shows the one load @ 23.5grs. of IMR SR 4759, I would probably start @ 21 or even 21.5grs. (-10% & -9%, respectively), instead of 20grs. (-15%), not enough pressure can be just as dangerous as too much pressure. 21.5/22/22.5/23/23.5grs should give you a good reference to start "fine tuning"...