the ARR33 is the M16, the KF7 is the AK47. They use completely different cartridges. M16 uses .223 or in the metric system version- 5.56MM, AK47 uses 7.62x39mm. The .223 round propels a lighter, smaller projectile packing less stopping power than the 7.62x39mm round, but better penetration. Trust me guys, I'm an expert in small arms.