Originally Posted by ThunderCactus
The barrel wont add any range, and it'll only increase accuracy if your current barrel is bad.
This is the most important line in this whole thread. By increasing your accuracy compared to a bad barrel a good barrel will increases your effective range, but it does not increase the maximum range where the BB will fall and hit the ground.
Also, lapping has proved to increase accuracy in crappy stock barrels, but no one has come up with convincing evidence that it increases the accuracy of high end stainless steel barrels. However, whenever you lap your barrel, you are also cleaning it thoroughly, which could result in a temporary increase in accuracy.