BREVETTATA Model 999 .22 Cal.

To the best of my knowledge my dad brought this pistol back from WW2.

It's says MADE IN ITALY BREVETTATA Model 999 Cal. 22. Engraved B40032 above the cylinder. Has the word MONDIAL engraved on the left side of the pistol, blue 8 shot double action pistol, 2 1/2" barrel, overall length is 6", with white plastic pistol grips. Seems to be only fired with blank 22 cartriges as the barrel is not smooth bore.

How old is it? What was it used for? How much is it worth?

Thanks for your help.......Rich