The 3:2 macro was designed to increase DPS at the expense of mana. This macro has also been referred to as the 2:3 or BM /cast macro. It works fairly well for both MM and BM hunters. Slower weapons even show a greater advantage by using this macro:

#showtooltip
/console Sound_EnableSFX 0
/cast !Auto shot
/cast Steady Shot
/cast [target=pettarget, exists] Kill Command
/script UIErrorsFrame:Clear()
/console Sound_EnableSFX 1