Michael Zeleny cite Armbruster et Kessler :
SIG P49 Military Deliveries:
The deliveries of military P49 pistols began in September of 1949 and ended in the early Seventies, adding up to 113,110 pistols.
The 4th KTH order began with A109711 in 1952. The range from A109711 through A120500 is transitional.
The range from A120501 through A213110 comprises the most common final Swiss military pattern.
Erwin Armbruster & Werner Kessler, Begegnungen mit einer Legende - SIG SP 47/8 / P 210, Kessler Waffen AG, 2007, lists the following P49 variations on p. 201:
First contract: A100001 to A103200.
Hammer without a safety notch; polished surface, grooved wooden grip plates, checkered slide stop, smooth safety lever.
Second contract: A103201 to A107210.
Hammer without a safety notch; polished surface, grooved wooden grip plates, checkered slide stop, smooth safety lever.
Third contract: A107211 to A109710.
Hammer with a safety notch; polished surface, grooved wooden grip plates, checkered slide stop, smooth safety lever.
Fourth contract, Ausführung a): A109711 to circa A120000.
Hammer with a safety notch; sandblasted frame, slide with brushed finish gradually phased out, grooved safety lever from circa A114000, plastic grip plates.
Fourth contract, Ausführung b): circa A120000 to A213110.
Hammer with a safety notch; sandblasted frame and slide, grooved safety lever, grooved slide stop with curved thumb shelf, plastic grip plates
Le tien est certainement du milieu des années '50, et si ses plaquettes bakélite sont celles d'origine, il se peut que les 2 derniers chiffres de l'année de fab' (des plaquettes) soit indiquée, en général c'est "matching years"