(I had to copy-and-paste your post into a text editor to read it: the text is not wrapping for some reason.)
The only Metnitz I can find is in Carinthia (Kärnten in German), which to the best of my knowledge has never been "Russia occupied", especially not in the peaceful 1880s. Do you have a reason to think your grandfather was born in some other town with the same name?
Come to think of it, what is your source for his birthdate and place? The church registers for Metnitz (and for Vienna) are on Matricula Online, and I can find no Jakob baptised in February 1887 in them. (In fact, I paged through 1886-1890, and none of the Jakobs I found can be your grandfather.)
There's no way I'm paging through anything in Vienna (waaay too many churches!), but a lot of it is indexed and searchable on GenTeam (registration required, but it's free). However, it's not coughing up a Jakob Scheer in 1850. Again, what's your source for this date, place, and name?