If a thick walled stamped guns give you a light, but strong receiver, is it true that a thinner milled receiver would be lighter and still be just as strong as thicker/heavier milled guns?  

I know that stamped receivers range from 1mm to 1.6mm or more, but I cannot find any spec for milled receiver walls at their thinnest point.

The reason I ask:

I have been looking around at used milled guns and already own some Arsenal milled.  Some of the variations have been quite extreme with some guns having very thick walls and others thin. Does anybody know the spec for thickness of milled receivers?  I am assuming that milled steel cracks if too thin and stamped merely flexes. May be an issue with an older gun...

I have only been able to measure the Arsenal that I have and the range between 3.9mm and 5mm at the thinnest areas.