Why did Mauser in the 70's

[Vlim]

Michael:

-Creating a uniform frame curve that works with all barrel lengths and both 9mm and .30 luger.
-Introducing castings as cost-effective alternative for previously milled/machined small parts.
-Allowing interchangeability of parts beyond a level accomplished by earlier manufacturers.
(the only 2 parts that needed to be 'mated' were the receiver and the rear toggle part).