Before including the Russian BMP-1 troop carrier, one might want to consider how much the first use of the airplanes have changed the battlefield. No battle since WWI has been fought without airpower. If I had to narrow it to one aircraft I would consider the Me 262. Most fighters since WWII are based on its jet powered swept wing design. Also one should consider the machine guns of WWI which replaced the bolt action rifles. The submarine, especially the nuclear ballistic sub which can stay on station almost indefinately and strike from hundreds of miles away without being detected, changed the way the USSR thought about a first strike survivability against the US. And finally the Little boy atomic bomb. The world has been and will always be under the cloud and fear of nuclear weapons because of this one device. Judged against these weapons, the BMP-1 making the list at number 3 or even at all seems a little ridiculous.

And If I may, the AK 47 is a superior weapon but it is just an infantry rifle. One should consider the Browning 30 and big brother 50 cal as more deserving. These weapons were not only infantry weapons but were used on personnel carriers, tanks, and were placed on truck beds as anti aircraft guns. They were even placed on naval ships, PT and river boats and in aircrafts such as bombers and fighter. They are still in use and are a much older weapons system. As a top ten infantry weapon, definately. AK and M16 number 1 and 2.

The BMP-1 is very much an important turning point in the weapons of the world - remember in all truth exactly WHAT it did - it changed the whole infantry doctrine further than WW2 did, courtesy of Heinz Guderian and the Mechanized Infantry unit. The BMP was the first to fully enclose its infantry in an NBC Environment, it covers WATER without conversion, it is designed to cover harsh terrain without much preparation at all. The sheer design turned, as they cite, to bring out other modern designs, like the Marder, the Warrior, and others.

The Me-262 I have to agree on, because it DID change the nature of the fighter in all truth and honesty. That would be more of a changing force than the Nimitz for certain.

The AK-47, I agree, Mack, was HORRIDLY undercounted - the AK-47 as you pointed out has been the right hand of change in this world, since its inception. You, Marinebrat, may think it's just an infantry rifle, but it is at times the SMALLEST weapons that make the BIGGEST impact - consider that it has been the right arm of damn near EVERY revolution in the world, is reliable as hell, easy to operate and maintain, and has at times been on both sides of the conflict. If there is ANY weapon that has deserved the #1 slot it was the AK-47, hands down.

Other weapons I think might have been missed, drastically, would be weapons such as the Soviet R-36 ICBM, the weapon that had such throw weight and range it STILL to this DAY stands unmatched, its also the forefront reason why the START treaties were put forward, to limit and reduce the number of the massive R-36 missile.

Other thoughts that could mention the change of the world would be EARLIER carriers, as they changed the whole concept of naval warfare into the warped monstrosity it has become, like Kaga or Akagi, the heavy carriers that struck the truest blow into the definitive clarity of the Carrier's firepower on the naval field. The V-1 or V-2 could also be considered major weapons that changed the world - V-1 being the first Cruise Missile in the world, V-2 being the first true Ballistic Missile. The Kirov Class CGN would be a potential, as they've led to the change in doctrine to consider them as a constant threat. The Sea Dart Missile changed doctrine in a measure, as it was the first SAM to intercept a sea-skimming Antishipping Missile. JDAM would have been less of a choice, in truth, compared beside, say, the PAVEWAY or other Early guided bombs - they were a new concept, they changed the concept of the bombing raid.

The Biggest thing is, that at times the Pinnacle weapon may indeed change things, but quite often people are ignoring the True groundbreakers. Hell, the Stg-44 could have been a runner beside the AK-47, since it was the first true Assault Rifle, but the AK weighs in heavier just by its sheer Proliferation and Effectiveness. It's seen more armed conflicts than essentially ANY weapon in the world.