Actually the 5.56 was always much more effective than the 7.62x39. To say the 7.62x39 is more powerful is very ill informed or just ignorant regardless of your personal opinion. 50 years of combat, testing, hunting and the facts of wounding bear this out. 40 years ago the Soviets and more recently the Chinese switched to cartridges similar to the 5.56 NATO. In spite of the backwards thinking that just bigger holes matter, it is energy, bullet placement and construction that matter. There are factors and situations to consider, a 7.39 may have more penetration in certain situations but it does far less damage.