When it comes to the number one assault rifle, AK-47 takes over all other rifles in one aspect: reliability. A study on the rifle proved that an AK-47 can be used even after it has been driven over by tank, filled with mud and water or covered with rust. The world’s most widely used assault rifle, the AK-47s have killed more number of people than any other assault rifle that ever existed. Beside the reliability factor, another reason why AK-47 is notoriously popular is because it comes cheap and there are a lot of fakes in the illegal markets around the world.