They didn't want to have any copyright issues on their hands?
soem guns they used, otehrs they didn't.
and actually, you're a dumb f**k for taht nato stuff man, that bullet size is just a standard NATO size, along with several others.
liek teh m4's 5.56 (or whatever), go read soem gun websites if you want to understand it.
alot of teh bullet sizes etc are counteracted by the amount of pressure teh gun fires the bullet out with.
the ak fires it at around , oh i don't rememebr, this is a lame thread lol, as I bet no-one here really likes cs taht much, and they care even less about what kind of bullets teh guns use.
go to CS's website, or liek i said, some gun nut sites to understand more about guns.
ak-47 manual:
http://www.fortunecity.com/olympia/wagner/137/ak01.html