Yeah, it's that heavy AK bolt warping the barrel (No, seriously, saw a slow-motion version of an AK firing. The barrel TWISTS when it fires.).
Of course, the two weapons are designed on different ideas. Assault Rifles are Rifles (Sort of) that can be Light Machine Guns (Sort of).
The M-16 is designed to be a rifle first, and a LMG second. Accuracy over suppression.
The AK is designed to be an LMG first, and a rifle second. Suppression over accuracy.
There's also the fact that the AK is so easy to use a child can do so. (And they do.). Can the M-16 make that claim? Would it want to is the next question.
Finally, the M-16, being light weight due to aluminum and polymer furniture, isn't so good in CQB, is it.
The AK? Steel and wood, worst case, you can use the damned thing as a club and put a load of hurt on someone. Also better for bayonets.
But I'm heading back to WWI with talking about bayonets.
Back to magazines, I wish we could get a statement about the M22/M23 family if their mags are interchangeable, along with the AK-family in Shadowrun. Also, the Ares Alpha/Beta/Sigma series of rifles, same deal?
EDIT: Hey, does the M22/M23 family have a AR-Version as well, like the M-16 family has the AR-15?