From your experiences, might be the Mags have more leaks.
Some places, it's possible to leave the light and the batteries separately. Put the batteries in, at time of use. Other times, that's not practical.
Christopher A. Young Learn more about Jesus
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It could be the spring. Never thought of that before.
Personally, I always thought it was because Mag-Lights are so well-sealed internally: No air-flow.
I've had a number of Mag-Lights ruined on account of leaking batteries over the years, but never in that same span of time have any of my ordinary flashlights suffered from that problem. Same Duracell or Energizer batteries in all, too.