Wire Saws are an interesting topic. BCB, who makes one of, if not the best wire saw is guilty of goofy marketing. They have this kid or a baby-faced man cutting through a tree limb or log or whatever with the saw basically in a horseshoe shape. You combine that with the natural heating that will occur when cutting with one of them and you are going to have a broken wire saw. Another problem is, not all wire saws are created equal. Les Stroud had an obvious cheap wire saw in one segment, broke it straight away and condemned all of them as a result. If the wire saw is attached to some sort of swivel (like fishing gear) via a small terminal clamp for wiring harnesses, etc., it's going to break.
The BCB is braided wire, folded over and then crimped with a steel or some other alloy, miniature cable fitting-sleeve. So are the Vietnam-era Varcos and the newer Varcos I have. (The Varco is not the same braided steel design but the attachment, how the loop is formed is steel cable sleeve.)
The M2 wire saw, like the Varco, has a National Stock Number and has been issued. It's quite interesting as well. If it breaks, you can still use it because it has a set screw you can loosen and then take the broken piece out and just set the wire back into it, etc.
Going back to Vietnam or right after Vietnam with the M2 and some other wire saws, the user is always reminded to make a bow saw type of device out of it using a section of sapling. I mean, they have a nice little drawing on the package. But so many people ignore that. These types of saws, assuming the higher quality versions, can really come in quite handy in certain situations but they're not for people who are going to put them through extreme angles or heat them up, you have to use them like a bow saw and go slow. It's not a chainsaw, after all.
I remember months ago, one guy in here just flatly stated that Doan Magnesium/Ferro firestarters were no good because he couldn't start a fire with one of them. I have almost a half dozen of them now and still have the original one from back in the early-to-mid 1980s when I bought it. I was a hardhead as well, I thought a little bit of magnesium dust and POOF! I will have fire. When I extracted my head from an unpleasant place and actually took the time to learn how to use the thing, VOILA! It works well.