In 1938 and 1940, modifications were designated PPD-34/38 and PPD-40 respectively, and introduced minor changes, mostly aimed at making it easier to manufacture.
在1938年至1940年之間，PPD透過進一步修改後被命名為PPD-34/38和PPD-40，並引入了細微的變化，主要目的是使其更易於生產。