Stamped versus milled receivers for integrity in AK-47's?

[His lordship.]

I know from my reading that the Russians started out with a milled receiver, then went to the stamped construction to save weight of the rifle during the 1950's.  And from pictures seen around the world today I can see both stamped and milled AK-47s.

Why are both methods used on a 1950's dated design to this day?  While logic dictates that milled may be better, in this day and age gun makers are using castings and plastic to do the job, instead of the old early 1900's method of extensive milling from a solid block of ordinance grade steel.

Have there been any tests for longevity done between the two methods of receiver construction, and in general, how many standard rounds will an AK-47 put up with before major failure (worn out), not counting minor parts, springs, etc. done with the7.62 X 39 cartridge in a controlled environment, and factory issue, without a recoil buffer for the receiver, or padding on the stock say, with the common stamped receiver in particular?

Thanks

[Jack Crevalle]

I was watching a show on the history channel about the AK-47 and they actually tried at first to make the receivers using stamped parts but apparently their metallurgy wasn't up to it so they started making milled receivers and then eventually made stamped ones.

Using stampings isn't usually done on military weapons to save weight. It was begun as a way to save time in wartime production, use less operations, on cheaper machines and using less skilled labor. Weapons are now designed from the get-go to be easily mass produced.