considered by many to be the greatest assualt rifle ever made. it is still in use in almost every communist and former soviet satalite country but in an updated form. the original fired a 7.62(.311 cal.)by 39mm the 39mm refering to the length of the brass or steel rimless casing that contains the powder and ignition primer for each bullet.this round was originaly designed for the SKS rifle and the round itself is in fact inpired by the german STG-44 the first real assualt rifle. contrary to the popular belief, the STG-44 actually had little to do with the AK series rifle, and actually was the basis behind the heckler and koch series of guns such as the G3 or the MP5. the M1 Garand actually had some design incorperated into the AK such as the bolt locking mechanism. later models of AK were 5.45x39mm and now they are using NATO round of 5.56x45mm.there have also been machine pistols, submachine guns, light machine guns, pistol, and sniper rifles based of the original design by mikhail kalashnikov.
the avtomat kalashnikova series of rifles are easy to manufacture as the reciever is nothing more than stamped sheet metal. the reciever was previously the hardest part to manufacture on any gun before the german MP-40, a 9mm para submachine gun that was one of the first guns made with main parts made of stamped sheet metal, such as the reciever.
because of loose tolerances during the manufacture the AK is the most reliable assualt rifle. its acuracy may not be as great as the M-16 series rifles, but it ability to hold up under all conditions without cleaning supasses it flaw in accuracy. the round the original AK-47 shot was a 7.62 round similar to a 30/30 winchester, a very popular deer round in america, which obviously is a .30 caliber bullet. while the newer AKs and the m-16 and all NATO assualt rifles shoot the 5.56mm a high powered .22, you may remember hunting small game or target shooting with one of these(same bullet size, but the NATO version has alot more power). in most high powered rifle states, you are not allowed to use any caliber of that size because it cannot effectively take down a deer like something of a .30 caliber can. basically all that means is the 5.56 is not as effective as the 7.62 for a deer or man sized target, so it will take more 5.56 bullets to bring one man down versus a 7.62.
the recent romanian made imports, one of which i own, are not the best AKs yet they achieve about 2.5 MOA with good ammo. MOA mean that it gets _"groups at 100 yards. so my AK-47 shoots all of its shots within a 2.5" diameter circle. to keep in mind that this is a fully automatic assualt rifle and that it was not meant to be accurate like a sniper rifle.
7.62x39mm = 30/30 winchester good for deer and man sized targets
5.45x39mm = similar to 22-250
5.56x45mm = the civilian version is the .223 remington not suitable for anything bigger than ground hog, but legal to hunt coyote with almost everywhere.