I don't know what the current situation with Mag, but it used to be the case that the insides of the Mag lights were untreated aluminum, where at least with many SF models, the inside is has a coating to prevent corrosion.

I grew up in SE Alaska, and I can say that I was plagued with the Mag corrosion issue with the lights that used big cells ("C" and "D").

I'm not sure I ever saw this with the "AA" lights, but those were likely to be kept in my bag or on my person, and probably kept warmer. I also kind of recall the coating might have gone on the inside on the AA models, but am too lazy to dig in my box to look.

I think a lot of the failure issue has to do with the use and storage of the large alkaline cells in cool and damp conditions.

I also had a lot of issues with contacts and the Mags in this environment always required a bit of fiddling (disassembly and cleaning the contacts). This affected both the big lights, and the AA and AAA lights.

In general, I would probably first avoid using large cell alkalines in applications where you are going to be storing the light in cool and damp conditions for long periods of time and expect the light to work.

In addition to the problems with corrosion the big cells like the "D" cell, while they contain a lot of "power", deliver it miserably. You really need regulation to use these cells effectively IMO.

In general, while Mag was a pioneer in its time, I find that they have not grown and their lights are underwhelming in the modern context.

They have too many parts, take too much fiddling, have less robust waterproofing, and so-so performance.

-john


Edit:

Some general lights that make good replacements for Mag lights - Fenix and Inova.

For cold damp environments, consider the Surefire G2 or G2 LED. Polymer, lithium technology, very reliable, and waterproof.

If you really want to stick to alkaline in a wet cool environment, consider 4xAA offerings by UK, Pelican, Princeton Tec.