Probably manufactured by DWM. – G. Teschner Co. was absorbed by Wilhelm Collath & Söhn in June 1906 and from then on was known as TESCO (TESchner-COllath).  It is believed that prior to ca.1905 RWS manufactured the W. Collath cases.  Teschner were well known for their series of lead bullets with copper jackets.  The base of the projectile is stamped with the letters C.F. denoting Collath, Frankfurt  A/O (on the Oder River) , Germany. (Ref. European Sporting Cartridges Vol.I by W.B. Dixon)