On 23 January 1917 Guynemer scored a "double" credit of victories 26 and 27 -first shooting down a Albatros C (Captain Martin Korner Killed) and then a Rumpler C I of Flieger-Abteilung (A) 216 in flames {Crew Lt. Bernhard Röder and his observer Ltn. Otto von Schanzenbach killed}. On 26 January 1917 Guynemer forced down an Albatros C.VII of Fl.Abt {A} 226 {crew captured} for his "30th" credit. On 8 February 1917, flying a SPAD VII, Guynemer became the first Allied pilot to shoot down a German heavy bomber (Gotha G.III) his 31st "Credit". On 16 March 1917 he brought down his 32nd "Credit" a Roland D.II of Jasta 32 {Pilot POW/DOW}. On 14 April 1917 he downed his thirty-sixth "Credit"-killing the crew of Fl.Abt {A} 254. His greatest month was May 1917, when he downed seven German aircraft including a quadruple on 25 May. By July, he began to fly the Spad XII; his "avion magique" was, at his behest, armed with a cannon whose barrel fired through the propeller shaft. It was also armed with a air-cooled Vickers machine gun. Although the cannon promised devastating firepower, the new plane was a handful because of it, as the cannon's rearwards-protruding breech mandated separate aileron and elevator controls, split from each other on opposing sides of the cockpit. The single shot cannon had to be manually reloaded in flight; it had a heavy recoil when fired, and filled the canopy with fumes from every shot. The Spad XII was not a plane for a novice pilot. However, Guynemer used it to down an Albatros fighter on 27 July, and a DFW the next day. The latter triumph made him the first French ace to attain 50 victories, "Fifty machines destroyed! This had been Guynemer's dream."