Originally Posted by manta
Its not always about bigger is better. The 7.62 is more effective than 5.56 but it also has more recoil in bigger and heavier allowing less rounds to be carried. The 9mm is the best all round handgun ammo. You will also find that .45 is only really popular in America the rest of the world is happy with 9mm.
There's a reason for that, and it's not because the 9mm is better.
The 9mm was created in Europe, and was eventually adopted by many countries for military and police use. Which naturally made the 9mm extremely popular in those countries.
The 45 ACP on the other hand was created in America, and was used by our military for 80+ years. It was mainly used in the 1911, which became the most popular handgun design in America.
That's the reason for the difference in popularity.