Velocity-wise, consider that a 5.45 is going at the same speed as .223 from a 16" barrel AR-15, which seems to be the current most popular setup of the AR platform.
Also, for 7.62, a lot of the new-production ammo uses a M67 design bullet. Section a bullet from Wolf, or Golden Tiger, or Bear ammo and you will find they all have a hollow cavity in the first 1/3 of the bullet. Thus, on impact they all will tumble like the M67 and produce a nasty wound. I think I recall that the soviets switched to that design of bullet in 1967 to enhance AK terminal performance, and naturally all client states followed suit. The 7N6 is just a further improved version of the M67-type with the major change being a mild steel spacer to act as knocker to further increase the rate of upset of the bullet.
What is interesting is the successor to the 7N6, the 7N10 has the front cavity filled with lead as well. I can't recall where I read but it seem that the steel spacer and the weight of lead behind it act to squish the lead in front and cause the bullet to mushroom similar to a soft-point on impact. Nasty but neat trick if its true.