In my notes Johann Sigott is first mentioned in 1898 and his last prewar gun is from the middle 1920s.
He or his son is on the 1945 list of Ferlach gunmakers and last Johann Sigott gun is dated 1962.
Another Sigott was Thomas, active circa 1910.
My notes are incomplete of course.
If proofed in Ferlach in 1931 your gun should have the single headed republican eagle with hammer and sickle.
Are the barrels marked JS by any chance?
Your gun seemingly experienced German reproof in January 1998, likely when the chambers were lenghtened to 70mm.

With kind regards,
Jani