Another change in the magazine design involved the treatment of the magazine feed lips. The magazine lips underwent a special hardening treatment to make them stronger. In October 1944, Walther decided to skip this hardening process.
Magazines produced by this new design were marked with a U under the P.38 marking. The U is a German abbreviation for ungehärtet and translates to unhardened. All Walther magazines produced by this process were of the enlarged design and were therefore also stamped with the v marking. Walther magazines produced without the hardening treatment were probably introduced into production in November/December 1944 and were stamped with P.38v/U on the left side of the magazine housing.
These magazines are correct with ac44 pistols in the K- and L-block and with all ac45 pistols.