Originally Posted by FlukeLSX
AK74 is based on AK47 design it still has the performance you would expect. SKS's are actually based on AK design. However, I've never heard anyone describe the SKS's as reliable as the AK line.
5.45 is more accurate, 7.62 has more penetration power.
5.45's are designed to kill. Being a lighter weight round, they are infamous for tumbling and bouncing off bone inside the body. So their killing power is high. While 7.62's will not always kill and were designed to penetrate bullet proof vests and walls.
Actually the SKS was designed and saw trials during WWII, the AK was designed later, they are totally different and neither is based on the other. The 7.62x39 was based on the 7.92x33 kurtz as a lighter recoiling 7.62x54R, more suitable for battle. the 5.45x39 was designed after the 5.56x45.
You are correct about the accuracy vs penetration though.
5.45x39 is cheaper, recoils less, is more accurate and is more suitable as a 'combat' round.
7.62x39 is better for hunting (with proper ammo)