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The 9×23mm Winchester is a pistol cartridge developed as a joint venture by Winchester Ammunition and Colt's Manufacturing Company.〔(Jane's Ammunition Handbook - 9 x 23 Winchester cartridge (United States) )〕 The 9×23mm Winchester has a convoluted development history, but was commercially introduced by Winchester in 1996. Marketed primarily to competition shooters as a replacement for .38 Super for International Practical Shooting Confederation, United States Practical Shooting Association and International Defensive Pistol Association competition, the cartridge made a splash, but never really caught on. The critical design feature of the 9×23mm Winchester is a much-strengthened case that does away with the semi-rimmed case design of the .38 Super which sometimes caused feeding problems. The strengthened case allows the 9×23mm Winchester to operate under a higher internal pressure, 55,000 psi (measured with a piezoelectric transducer), in comparison to the maximum pressure of 36,500 psi for the .38 Super (current SAAMI standards). It has a slightly tapered but nearly parallel case which means that it has greater magazine capacity for the same 9 mm bore diameter relative to the necked down cases of the .357 SIG, 9×25mm Super Auto G, or 9×25mm Dillon. To achieve enough propellant capacity for the power needed the 9×23mm Winchester is longer than the 9×19mm Parabellum or .357 SIG and so requires the extra magazine front to back length of a 1911 style magazine. ==History== Patent 5,187,324 was filed by John Ricco of CP Bullets in 1992 for an "improved 9mm cartridge casing" that he called the 9x23 Super. He had the prototype brass casings made by Winchester Ammunition. They then modified the design slightly and filed it under patent 5,507,232 in 1995. In comparison to the popular 9×19mm Parabellum, Winchester had lengthened the overall case by 4 mm and made it much stronger. They named it the 9×23mm Winchester. In comparison to the long established .38 Super Auto, also a 9×23mm, the new cartridge was rimless rather than semi rimmed. Announced to the public in early 1996 at an NRA convention, the 9×23mm Winchester cartridge was claimed to have the lowest recoiling load and still qualify for Major Power Factor designation in the IPSC.〔 The IPSC Power Factor (PF) is equal to bullet weight in grains times muzzle velocity divided by 1,000. A PF of at least 175 was needed to qualify as Major within the Power Factor designation used within IPSC competitions. A Minor power factor carried scoring penalties and so there was an incentive to make the Major qualification. As the power factor calculation is proportional to bullet momentum and as the very large proportion of recoil is proportional to bullet momentum, it is immediately clear that the 9×23mm Winchester had essentially the same power factor and recoil as .45 ACP. The true benefit of the 9×23mm Winchester came from two things. Firstly, more rounds could be fitted into the magazine and that, in general, allowed fewer magazine changes to be made in the course of a contest task spread over multiple targets. Secondly, the higher operating pressure of the 9×23mm Winchester meant that a compensated pistol, where holes or slots in the barrel project high pressure gas upwards before the bullet leaves the barrel, had a greater ability to reduce the upward flip of the muzzle under recoil. That meant that users of the 9×23mm Winchester were able to return to target in less time than with a compensated .45 ACP pistol of otherwise identical design. Since speed was a major element in the scoring system within IPSC competitions there was an obvious advantage to the 9×23mm Winchester over the .45 ACP. This double competition benefit of the 9×23mm Winchester was the motivation behind Ricco's design and Winchester's production of its almost identical twin. Because Ricco had used Winchester to produce his prototype cases and they had then used the design themselves, Ricco was able to sue Winchester and after some 7 years he won his case.〔(Pistolsmith Profile - Dane Burns )〕〔(Ammo Types )〕 The 7 year delay to production caused by the court case effectively killed the cartridge because the IPSC had changed the power factor boundary from 175 to 165 before Winchester started production. The reason for this was that many pistols based on the 9×19mm Parabellum, the 9×21mm loaded with the bullet further forward and the .38 Super Auto (also 9×23mm) were being used beyond their safe pressure limits for the same reasons that made the 9×23mm Winchester so good. Many were blowing up and so the IPSC reduced the power factor boundary to one that could be reached with those cartridges in safety. When the 9×23mm Winchester came to market with its much increased pressure ceiling, produced by thickening the web section of the cartridge case, it was no longer needed. Without the court case delay the power factor might not have been reduced and the 9×23mm Winchester would probably be the majority choice in IPSC Open division and a very successful niche cartridge rather than a minor niche cartridge. As it is perceived as a purely competition cartridge it has made almost no penetration into the self-defense world. This is an unfortunate perception because for the same recoil as a .45 ACP pistol it produces much more kinetic energy and it would be very effective for self-defense. 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「9×23mm Winchester」の詳細全文を読む スポンサード リンク
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