machine guns

[AlienXXX]

Hello fellow SP players,

MAybe some of you can offer some advice.
In my previous experience playing SP against the AI and in more recent times playing human opponents, I must be doing something wrong when using machine gun units...

I tend to find that these units get routed very easily. If they come under fire when dismounting from a vehicle that is usually it.
Infantry units are a lot more resilient, and even other units such as bazooka teams don't seem to be so fragile.

I know the theory is that mguns are supposed to be outside rifle range and provide area and support fire. But in the battle field with all the smoke etc, usually I do not have the luxury of such a long line of sight that I can often position my mguns so far away.

Are mguns in SP meant as stactic units for perimeter defense only or am I doing something wrong?
How long does a mgun unit need to stay in one place before it gets "dug in" status?

Thanks
Cesar / AlienXXX