http://www.bowonlyoutdoors.com/broadheads.html

There is also another test where they shot fixed and mechanical through sheets of plywood and into a tire the expandables did very well some where ruined others held up. from the pictures I wass looking at the expandables had better penetration than the fixed blades. I have read other articles stating you should use expandables with an 1-1/4" cutting diameter you could go up to 1-1/2" and do well. It said anything much larger than that had issues with opening up. Also less messing around tuning expandables they fly closer to your field points less horizontal drift than fixed blades.

Remember:

BOWHUNTING IS NOT A MATTER OF LIFE AND DEATH...... IT'S MORE IMPORTANT THAN THAT!!!!! (PLAGIARIZED FROM A DUCK HUNTER)