Why exactly did Walther change the frame material from steel to aluminum and change the slide finish from bluing to parkerized? Was easier to mill out aluminum alloy and do parkerized finishes?
Do aluminum alloy frames wear out more than steel frames from heavy use in the long run? I could imagine that the alloy frames on the P38 and P1 could take more of a beating because of the locking block system.Weight and cost.
The standard reason you find everywhere for switching from steel frames is the weight reduction, somewhere close to 200 grams. Anodized aluminum is also cheaper. However, I suspect the increased need for repair and replacement likely wiped out the cost advantage for the customer agencies in the long run.
Here's an answer from FAQ: The ClassicsDo aluminum alloy frames wear out more than steel frames from heavy use in the long run?
The fat slide was Walther's answer to a high incidence of slides stretching, cracking, and eventually breaking, at the locking block cutouts. I have personally examined dozens of slides , both late-war Mauser and postwar Walther, cracked or broken in this way. Whether this was the result of more powerful or widely variable postwar 9mm Para ammunition or of some other cause, I am unable to say.
I do not believe that cracking of the frame was or is a frequent occurrence. I personally have seen only a very few, cracked in different places, from which I draw no opinion as to the cause.
The hex lug was added for an entirely different reason: to extend the service life of the frame by providing a hardened steel wear surface for the locking cam. Frames that have seen a lot of use, especially when dirty or without lubrication, show considerable wear and displacement of aluminum at that point, which makes the action locking/unlocking rough and less consistent and reliable.
The hex lug does not make the frame stronger; it is only an insert and does not "cinch" the frame together to prevent splitting. It could be argued that broaching the hole for the insert actually makes the frame integrally weaker. But it lasts longer.