The transliteration is;
Gewehr = Rifle.
Blattchen = Sheet (as in paper)
Pulver = Powder
A translation is Flake Rifle Powder.

I don't know what St. M.G. would stand for. Sorry.

And yes, cased bolt shroud and safety are not uncommon.

A don't know if it's a New Your importers rifle or not. I don't have any knowledge of that.
Not much help....am I?