Carrying Weapons by the Carrying Handle

[Gerowen]

I have a question for those of you in the military that I've never had answered for me.

 

Starting in basic training we were always taught never to carry M-16s/M-4s by their carrying handle.  My question is, why?  We had it beaten into our heads that the proper way to grab or carry it is by the barrel shroud, and using my own personal M-4, I've carried it by the carrying handle, and once while I was walking in the woods, I even fell with it in my hands and had it bounce off a log, and when I got it home I fired a few rounds and it held zero, so it doesn't appear that carrying it by the carrying handle has any affect on the zero of the rifle.

 

I know some of you may have been drill Sgts, so I'm curious if there's really a "reason" for telling soldiers not to carry their weapons by the carrying handle, or if it's just something that's been passed down that we all say just because everybody else has said it before us.