MAS Model-50 Air Pistol.
With thanks for these pics to LeonardJ. He said of this pistol:
"I managed to find this interesting variant of the French MAS 50 training pistol several years ago, and despite my best efforts thus far, have still not found another like it. Most published information that I had found to date offers the same description, in particular the details regarding the markings and the grips. Could this particular pistol be one of the rumored "civillian" versions of the MAS 50?
In this pic of the LHS of this particular gun, two things become immediately obvious. The lack of the factory markings that are usually stamped into the frame just below the barrel, and the unusual coloration of the grips - a semi-opaque tortoise shell effect.
There are two possibilities for the lack of these markings on my specimen that come to mind - that it may have been arbitrarily missed by the stamping operation, or that the marketing people at the time thought that a "civilian" version of the gun should not have the military manufacturer's name on the gun.
The RHS of this specimen is marked in the usual fashion with "CAL 4mm5 - Mlb 1950" and further forward, almost directly beneath the front sight area, the serial number.
The usual markings on the LHS, referred to above, and missing from this gun reads 'MANUFACTURE NLE D'ARMES ST ETIENNE'.
The usual grip color is black."