Doubleriflejack, this rifle is more early than you think! As the ledger? number "635" shows, it was proofed by the Zella-Mehlis proofhouse in "2.12" = February 1912! The Suhl proofhouse did not apply such ledger numbers and Zella -Mehlis started somewhat earlier than Suhl to use mm dimensions for the bore diameter instead of the old gauge numbers.IMHO this rifle was made for Fischer in Berlin by the guntrade in Zella-Mehlis, a rivalling gunmaking town just a few miles, 6km north of Suhl, then sold by Fischer to Specht in Posen who finally retailed it. Posen city was German until 1918, since 1920 it is Poznan in Poland.
hipwr223, I would try to get some factory ammo first to try the regulation. Though the standard load is a 18g = 286gr bullet now, but this should be ok for your rifle. "Lighter" loads may not suit the regulation of your barrels, as lower-than-factory velocity will probably mke your barrels shoot apart while lighter bullets at higher velocity will make them cross.