Can't go wrong with the 30-06 using premium bullets.
When comparing a bullet's energy in a 30-06 versus a 300 Win Mag, if you put a premium 180-gr. Nosler AccuBond bullet in a 30-06 at 2,750 fps MV and compare it to a plain jane Winchester 180-gr. Power Point in a 300 Win Mag at 2,960 fps MV, the 30-06 AccuBond will have an amazing 104 ft. lbs more energy at 300 yards: that's right - 2,005 versus 1,901 (Source: Winchester's 2005 Ammo Catalog, p. 10 - 13).
So you see the 180-gr. AccuBond with a BC of .509 easily makes up for and passes the 210 fps velocity advantage the 180-gr. Power Point had because of its much lower BC of only .349.
In this case, the 30-06 180-gr. AccuBond outperforms a 300 Win Mag 180-gr. Power Point at 300 yards.
Aim for the Thoracic Triangle Area between the armpits & throat.