There proved two major artillery manufacturers for the German Army throughout both World wars, these being Krupp and Rheinmetall. After a period of reestablishing themselves during the interwar years, Krupp designed and developed the 15cm (150mm) Kanone 39 (K39) series gun for the Turkish Army prior to Germany's entry into World War 2 (1939-1945). The gun and its mounting hardware was sat upon a 360-degree rotating turntable platform which, in turn, was affixed to a typical wheeled carriage assembly. The turntable aided some in tactical flexibility by allowing essentially unfettered traverse though this element also added weight, a third major component to the gun when transported, and increased production costs. The Turkish Army originally ordered the gun as a dual-purpose field gun / coastal defense gun and also contracted for suitable ammunition from German suppliers. Design work began in 1938.
Only two examples had been delivered to Turkish authorities when the German Army officially committed to World War 2 by way of its invasion of Poland. As such, all manner of field artillery was now sought and any further production from Krupp of its K39 series guns was now taken on by the German Army. This also included any stocks of completed Turkish ammunition produced for the gun. Production eventually netted just 60 or so of these new 150mm systems (its precise caliber was actually 149.1mm) and manufacture spanned from 1939 to approximately 1942 before being given up.
Like many other guns of German origin, the K39 gave good, reliable service in the face of war. Its undoing was really just its limited production total. It also suffered the limitations seen in other guns of the period - weight and transport. The gun system broke down into three components for relocation and this included the all-steel turntable which complicated the effort some. Rate-of-fire proved low for gunnery crews which sought to put as much ordnance on a target area as necessary - even a trained crew netted just one to two projectiles per minute. The system weighed 40,300lbs in its travel mode and set up to weigh 26,900lbs. The barrel alone measured 28 feet long, a cumbersome length to handle repeatedly.
The K39 series utilized a proven horizontal block breech arrangement when loading/reloading its 150mm shells and the gun's recoil was countered through a hyropneumatic system. The weapon component was mated to a modern split-trail carriage featuring the typical two-wheel arrangement which allowed it to be moved by vehicle or beasts of burden as necessary. The gun's mounting held an inherent elevation span of +46 to -3 degrees for variable engagement ranges and traverse was 60-degrees (apart from the 360-degrees offered with the optional turntable). Range was rather excellent at 27,000 yards, giving crews a fairly profound reach on the then-modern battlefield. Muzzle velocity of the outgoing shells peaked at 2,840 feet per second.
However, the end of the line soon came for the K39 at its limited availability made it a non-standardized artillery piece in the inventory of the German Army. It went on to serve a role in as static defensive-minded coastal artillery piece along Hitler's "Atlantic Wall" when protecting the approaches from English Channel. Other examples were relegated to training groups until their lot was wholly removed from service.