Baking Bread Adjustment

I found that if I turn the temperature down from 500F to 450F when I remove the lid from my dutch oven after 30 minutes of baking, I can bake the bread for another 10 minutes. If I don't turn the temperature down, I get 5 minutes of baking. Any more and the crust burns. I assume this happens because the oven temperature drops when you open the door. The top element will turn on to compensate for the loss of heat thus burning the crust. By turning it down to 450F, you avoid the top element turning on.