[Hatchett]

When was the first, historical appearance of the C-Mag?

[Sunray]

The Germans used a mag like that on both the MG34 and MG42 before and during WW II.

[Jim K]

OK, I'll bite and look like an idiot, but whatinheck is a "C-mag"?

The only thing I can think of is the Thompson "C" (100 rd) drum.

Jim

[M2HMGHB]

C Mag is a dual drum type magazine that was marketed for various firearms including the AR15, M249, Mp5 and other firearms. The web page is http://www.beta-cmag.com/cindex.asp

Edited to add: The "saddledrum" that the Germans used on the MG34 and MG42 held a 75 round belt, they were not magazines just storage devices for the ammunition belts.