you also have to consider that M4A1 has only 1 more damage point. AK47 and M41 have both 20+ damage. this means: both weapons need only 5 hits (5*20=100) to kill a player without armor.
conclusion: the damage doesn't really matter at all in this case! the AK is as powerful as the M4A1 because you need the same number of hits to kill. The only negative point on the AK47 is the accuracy but this is compensated by the lower price.
in short:
AK47
price
accuracy (in most situations [when you fire at an enemy which is on your screen] it will not matter much)
M4A1
price
accuracy
damage can be considered as equal
balanced imho
(I'm not sure how armor will change this. I assume that you will still need the same number of hits to kill but I'm not sure and too lazy to check that)