While I was google-ing to learn how to zero an M16 rifle I found this website and thought that it might be useful for other people. I know it is meant for the real steel thing but I think this might atleast give some hint on the "how to".
http://www.armystudyguide.com/conten...a2-rifle.shtml
You can also find information on many other things regarding the uniforms, land navigation, maintenance and use of many equipment and many more.
Good reading!