alexk,
to inform you a little
I am 5,9 160 lbs. for me to hit one 300 is no big deal, I have gotten to the point where it takes 310-320 to feel like I really hit it well. for example, today hit driver, 7 iron, on a flat, no wind, 500 yard par 5, drove into the bunker of a 315 yard, 30 foot uphill par 4 I was 10 yards short of pin high. this has become pretty normal
for me it comes down to setting up properly, cupping the right wrist first in the back swing, and maintaining spine angle when I get to the top of the back swing. SEt up is the biggest of those three. The golf swing becomes complicated when the basics have not been taken care of