Magnesium handle A's were made from 1971 until 1977, or maybe 1978 also? Can't remember.
Magnesium handles are great, just factor in that they are lighter in weight, and though they shoot off the shelf fine, if you like a shelf low above knuckle, you will want to go with a wood handle, either type II Grayling, or modern ere (2002-present). NOt that Mag handles shelfs are necessarily high, just something to consider. Mag handles also have interchangeable grips, a Fred Bear patented concept, for low, medium, and high wrist grips.
When shopping for a Bear Takedown, always consider limbs and handle a separate purchase. If you see a handle with limbs and wrong draw wt, do not pass JUST because wrong limbs. It will be hard to find the combo of limbs and handle in exact stats you want. Good luck.
Best takedown system in the world, ever.