I've read interesting articles about WWII fighters armament. Many discussion here was made considering the kinetic energy only. That is a function of the projectile weight and the velocity with which it hits the target. BUT in german projectile there was a chemical factor. It is well explosed in that old article: "WORLD WAR 2 FIGHTER ARMAMENT EFFECTIVENESS" http://www.quarry.nildram.co.uk/WW2guneffect.htm Carefull read lead me to these paragraphs: "There are two types of energy that may be transmitted to the target; kinetic and chemical. The kinetic energy is a function of the projectile weight and the velocity with which it hits the target. This velocity in turn depends on three factors: The muzzle velocity, the ballistic properties of the projectile, and the distance to the target. There are therefore two fixed elements in calculating the destructiveness of a projectile, its weight and chemical (high explosive or incendiary) content, and one variable element, its velocity. The key issue is the relationship between these three factors. "If we compare the values with the few data known from ballistic tests, we have some indications that the factors assumed in the calculations are realistic. The 20x80RB M-Geschoss and the 20x110 (Hispano) HE were rated as about equal; the greater blast effect of the M-Geschoss was countered by the greater penetration and kinetic damage inflicted by the Hispano. They do indeed emerge with similar scores. Also, the Luftwaffe reckoned that it took about four or five times as many 20 mm shells to destroy a heavy bomber as it did 30 mm rounds. The power relationship here is 3.6 times for the MK 108 and 6.2 times for the MK 103, which neatly brackets this observation. Who wrote that article is a specialized man, with large knowledgement about guns and ammunition. So some adjustments should be done in Hispanos decereasing his power or in MG-FF / MG151 increasing his power. That's not a luftwhining but a fact well explaned for anyone.