Take a look at the subject article: http://www.gizmag.com/compbullets-faster-with-vents/20806/ According to the article an Italian weapons manufacturer has designed bullets with "holes" in them which reduces their drag, muzzle flash and improve bullet speed. They claim the holes allow the combusting gunpowder to "lubricate" the bullet within the barrel thus reducing friction and increasing exit velocity. What do you guys think? Personally, I call BS on the design. I cant say much about the physics inside the barrel, but I am confident that as the bullet travels through the air it will create cavity drag. See http://www.eng.uwo.ca/people/esavory/cavity.htm for an explanation. The problem is that there will be a low pressure region behind the bullet, as well as where the holes are located (this would not be the case if the holes where placed on the top portion of the nose near the body), which might lead to pressure oscillations. I would think these oscillations might increase drag and increase the "noise" of the bullet. I cant tell 100% from the pictures, but it looks like the interior of the "holes" are not rounded to facilitate smoother flow to the rear of the bullet. I am also thinking about longitudinal stability for the first picture shown. How fast does the bullet have to rotate to maintain a stable trajectory? Do these holes move the center of gravity too far forward? Will the drag of the holes increase windage (drag due to a spinning cylinder) and thereby reduce the angular momentum? But then again, aerodynamics and fluid mechanics is still a black art for unknown designs. May be these holes really do make a difference?