Another update has come from the CS:GO developers in which they fully explain hitboxes and the reasoning behind weapons appearing to be inaccurate.
A lot of the feedback surrounding CS:GO has been related to weapon inaccuracy where people feel as if they’re hitting the enemy but no bullets appear to be registering. In the most recent blog by the CS:GO developers, they explain that the reason for this may actually be the hitboxes design.
They note that in CS:S and CS 1.6 the hitboxes are fairly large, with CS:S having larger player models in comparison to its older brother. To create a balance of the two games, CS:GO has larger models but with smaller hitboxes which forces players to be accurate in their gameplay.CS:S HitboxesCS:GO Hitboxes
As you can see by the images the hitboxes in CS:GO appear to be a lot smaller than all other versions of CS in the past. This means that for all the regular players of those games, they have to adjust to the smaller hitboxes and be a lot more accurate when firing guns in order for the bullets to register.