Studies have shown that the speed the ball travels after being hit by a metal bat is 3 to 8 miles per hour faster than a wood bat. This would translate to a ball hit for a home run travelling 20 to 50 feet further off a metal bat as opposed to a wood bat. Click on the 'Metal Bat vs Wood Bat' link on this page to read a very interesting article about these studies that were performed on the two different types of bats.