already posted this in the "MP7" thread soz
Peeps/aperture sights like one the M16/M4/MP7 in this game are very hard to see people though, this is because the rare part of the sight (the peep part or the piece with a hole in it that you can see the front sight post through) obscures your view of your target.
Peep sights in real life are renowned for being the best type of iron sight for accuracy and for being able to see your target best. This is because with a standard "notch and post" sight like the AK/SKS uses you have to block out half of your target to be aiming at it, whereas the peep sight means that when you look through it, your eyes blur out the rare peep sight making it look like whats been nicknames "ghost ring", this provides a excellent picture of your target and what is below and all around him. sadly in insurgency the entire sight is in focus meaning you get a terrible sight picture.
I'm suggesting adding a "blur" mechanic to make sights (not just peeps sights, all sights) look more realistic and to make some iron sight actually usable eg M16A2 where there is no alternative.