本帖最后由 lixiaoyong 于 2017-3-17 16:14 编辑 |
DWM designed a 7x39 cartridge in the mid-1930s, for which a Walther self-loading carbine was reportedly made. It was appreciably more powerful than the later 7.9x33 Kurz. However, the interest of the Heereswaffenamt (HWA) was by then focused on Polte developments, so the DWM round also failed to progress further. RWS produced several short-cased rifle rounds in the 1930s, including an 8x45, 8x46 and 7x46, but these developments were taken no further. Rheinmetall-Borsig were involved in a number of prewar experiments concerning 7mm rounds in various case lengths, some of them very long, probably for high-velocity aircraft gun projects. One drawing has been found of a 7x36 cartridge which would obviously have been suitable for assault rifles, but there is no evidence that it was made. The design work may have been done by Polte on behalf of Rheinmetall-Borsig.
This brings us to Polte Patronenfabrik of Magdeburg, who made by far the most significant contribution. The HWA awarded them a contract, probably in 1938, for the development of a short-cased infantry cartridge. This resulted in several different designs of cartridge; 7.9x45, 7.9x30, two different 7.9x33 and a 7x45, all by 1940. In all of these, Polte retained the base diameter of the standard 7.9x57 rifle/MG round, and in all but the 7mm the same calibre as well. This kept production costs to a minimum and no doubt helped to account for the success of their proposals. The final 7.9x33 design (which had less case taper than the first or "transitional" effort) was approved in December 1940, the only subsequent change being to the angle of the extractor groove, which was altered from 45 to 60 degrees in May 1942.
The story was not yet over. Federov, the old pioneer and true father of the intermediate calibre selective-fire rifle concept, now "Doctor of Services, Professor Lt. General (Technical Engineering Branch) V.G.Federov" and serving as a senior member of the Technical Council of the NKV, continued to argue for a smaller-calibre cartridge. As a result, between 1946 and 1948 several different rounds were made and tested in 6.75mm as well as 7.62mm calibre. Despite this, the 7.62x39 M1943 cartridge was finally selected in 1948, when the AK-47 was already undergoing pre-production troop trials. One of the reasons for retaining the 7.62mm calibre was said to be that the Soviet manufacturing plants did not at that time have the equipment to mass-produce smaller-calibre ammunition and gun barrels with the necessary precision.