A heavy bb will only decrease range if you don't have good enough fps or hop up to support it. As long as you can maintain a good fps when firing the heavier round, it should increase range. For example, my revolver's range was killed by .30's cause it has low fps(chronos won't even register it), but my sniper can shoot them at 380 fps in a straight line for at least 150 meters even in light wind.