Regarding Concentric Circled On Navy Mags

[DonVoigt]

Originally Posted by Chickenthief

I think it is magazine spring tension, but!

Why did the marine have to teel 9mm mags from 7.65mm mags?
The Germans didnt adopt the 7.65mm in the first place and the marine only had mags for the 9mm.

I understand the difference would the the spring tension- that is the question- are they different, or more exactly were they manufactured differently.

There were changes in the shape of the shell lips and length of slot,
that is well known; but I've not seen any mag spring data.

Mainsprings were changed several times and the number of coils and wire diameter and number of turns are recorded.

This question does not apply only to "military" use, but also the many commercial models.