What the SLR /L1A1 was copied from.
Ah ok i see sorry, basically its the best because its been used for 60 yrs and a favourite with many gangs, terrorists, army's of Asia, Middle East, Africa, Far East, Eastern Europe, South America etc etc, to be blunt, all the fucking asshole parts of the world have been using it and getting it cheap as chips for decades, so it might not be the best weapon in regards to beautifullness and technology but it is certainly the best when it comes to cost, effectiveness, simpleness and favouritism amoungst the scumbags of the world.
Not the AK-47's fault for all the wankers that use it but it's made an impression that can't be beat.
I would prefer to use something else, and I do in Call of Duty