It does sort of look like it says 1930, doesn't it? However, like you said that doesn't make much sense. I'm no expert on Austro-Hungarian uniforms, but I know someone who knows a lot more and I'll refer this to him. Perhaps it says 190-something?

I would imagine it's not austro-Hungarian at that point in time. Maybe it was an old set of uniforms and guns photographed years afterwards. The AH Empire ended in 1919 when WWI ended.

So as far as I can tell the rifles pictured seem to be some variation of the Werndl rifle. This was the rifle that preceded the Styer-Manlicher in the Austro-Hungarian military. M. 1873 or 1877 carbine maybe? (Looks like only one barrel band, and also look like they may be a bit short for rifles of that day) According to Wikipedia the closest uniform I can find is for the Engineers. Those rifles weren't standard issue any more by the time WWI rolled around, however apparently they were used by some units. As for the writing, maybe it says 1880. That wouldn't be outside the realm of possiblilty as far as what I've seen. Do you know when your great grandfather was born?