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The 21 cm Kanone 39 (K 39) was a Czech-designed heavy gun used by the Germans in the Second World War. Two were built before the Germans occupied Czechoslovakia in March 1939 and seized the rest of the guns and kept it in production for their own use, eventually building a total of 60 guns for themselves. They saw action in Operation Barbarossa, the Siege of Odessa, Siege of Leningrad and the Siege of Sevastopol and were used on coast defense duties. ==Development and design== It was designed by Škoda as a dual-purpose heavy field and coast defense gun in the late Thirties for Turkey with the designation of ''K52''. Only two had been delivered before the rest of the production run was appropriated by the Heer upon the occupation of Czechoslovakia in March 1939.〔Gander and Chamberlain, p. 206〕 Unlike the German practice of sliding block breeches that required a metallic cartridge case to seal the gun's chamber against combustion gases, Škoda preferred to use an interrupted screw breech with a deBange obdurator to seal the chamber. This lowered the rate of fire, but had the great economic advantage of allowing bagged propellant charges that didn't use scarce brass or steel cartridge case when those metals were in short supply. The other unusual feature of the gun was that it used a monobloc auto-frettaged barrel. This was a single piece of steel that was radially expanded under hydraulic pressure. This had the advantage of placing the steel of the barrel under compression which helped it resist the stresses of firing and was simpler and faster to build since the barrel didn't require assembly as with more traditional construction techniques.〔Hogg, p. 100〕 The box-trail carriage revolved on a turntable that sat on a ball race on the firing platform and was capable of 360° traverse. The end of the carriage rested on rollers which rested on a metal track or rail. For transport the ''K 39'' broke down into three loads, the barrel, the carriage and the firing platform with the turntable. Each of these was carried on a trailer with pneumatic tires. Emplacing the gun took six to eight hours, mainly to dig in and anchor the firing platform.〔Hogg, p. 100〕 The story of the gun's development by the Germans is contradictory in the available sources. Hogg claims that the ''K 39/40'' had only slight changes made, but that the ''K 39/41'' added a muzzle brake to control recoil.〔Hogg, p. 100〕 Gander and Chamberlain say that the ''K 39/40'' and ''K 39/41'' both had muzzle brakes with better performance than the original ''K 39'' and that the ''K 39/41'' was introduced to simplify production.〔 A total of sixty were built for the Germans.〔(【引用サイトリンク】title=German Weapon and Ammunition Production 1 Sep 39-1 Apr 45 )〕 Nine of these guns were sold to Sweden during the war where they were used to equip three heavy mobile coastal batteries. The guns were part of the Swedish war organization until 1982 although training on them ceased in 1972. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「21 cm Kanone 39」の詳細全文を読む スポンサード リンク
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