Would 5-inch AA guns protect Hipper or the M class?

How much difference would a modified 12.7 cm dual-purpose gun make on an Admiral Hipper-class or M-class cruiser?

It might inflict somewhat greater aircraft losses, but it would not stop the British from attacking or fundamentally change the engagement.

The proposed 12.7 cm weapon is roughly a 5-inch anti-aircraft gun. Its larger shell might produce a more powerful burst, while its rate of fire could be slower than the existing 8.8 cm weapon. That trade might shoot down additional attackers, but the defensive effect would probably remain broadly similar rather than become a decisive shield. British aircraft would still launch the strike, illustrating why one improved weapon rarely overturns the wider operational balance.