martin08 - is that a captured Czarist Mosin?
Aragorn243 - we need a good photo of the markings on that bolt. As you noted, it is an odd place for a capture mark. And the fact that it is not a clean AZF sequence jars. But the AZ number series has been recorded as used by Brescia in 1918 (see "Il Novantuno" P.343). So it may quite simply be a mismatched or replacement bolt from a Brescia M91.
Photos please!