As this Drilling still sports the gauge number 118/35, indicating a bore diameter between 8.64 and 8.89 mm determined by the proofhouse, it was proofed in Suhl before April 1, 1911. The 9.3x82R Nimrod cartidge is commonly dated to 1905, so this gun may be dated 1905-1911.
"Nimrod", after the great hunter of the bible, was the trademark of Thieme & Schlegelmilch, Suhl.
The inscription "Nimrod Verschluss Patent" refers to the wedge-shaped reinforcements under the shot barrels that fit into recesses in the action bar. They prevent sidewais flexing of the barrel assembly on firing the rightor left barrel.
The "Nimrod" locks are regarded here in Germany as the most advanced form of side- or boxlocks. They were made by T&S both as sidelocks, trigger-plate (the rifle lock of your Drilling) and semi-boxlocks. On their sideplated boxlocks the lockparts were mounted on the frame under the sideplates, but were hand-removable after taking off the sideplates. Even a fitted mainspring-clamp was to be found in a recess under the sideplate! The Nimrod lockwork has two mechanical advantages over the "Usual" design:

The sear detent S'-A' is far away from the fulcrum of the hammer so there is much less pressure. Less obvious, but even more important: The linkage between mainspring and hammer forms a toggle joint that is almost straight when the lock is cocked, so the mainspring exerts little force on the cocked hammer. As the hammer falls, mainspring pressure constantly increases until the firing pin is hit. Both these features allow for a light trigger release without compromising safety.
9.3x82 Nimrod cases are available, sometimes, from Horneber.