ok well there is a difference between the Rifles and scopes. Ok well the first one is an ACOG. You DONT want you front sights to be seen and it is possible that it (which it must likly is) the ACOG is sitting ontop of the carry handle. In this position the ACOG sights are over the other sights to provide "back up ironsights".
The second picture looks like the Aimpoint scope is set on a rail. which would place it between the 2 sights makeing the front sight visable. Also the red dot is to the top of the scope so the guy is looking down... is he was looking straight through it would be in the middle and directly ontop of the front sight. (So seeing the front sight in this case makes sense)
Front sights are something you only want to see when you are using it ... if you saw your front sight in your ACOG your vision can get blurred and cause you to miss the target by making your eye loose focus .
http://www.rockriverarms.com/item-detai ... N=53770583
^Heres the one with the Aimpoint (2nd picture)
http://www.rockriverarms.com/item-detai ... N=53770583
^This is most likely the one with the AGOC *Standard A2* (1st Picture)
Disclaimer: The pictures shown are only to show a point. They are not supose to be the rifles that are being shown in this tread.