Don't know anything about Sabina watches I'm afraid, so don't know whether that was a military issue chrono or not.

The movement looks to me most like a Landeron 52 with a couple of modifications - maybe that's what the stamped "C" indicates, though I don't know of any versions other than the "base" 52. Of course, Sabina may have made some in-house changes to the Landeron ébauche.

Sorry not to be of more help, but that's quite a left-field watch!

Mark