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The .30-06 Springfield cartridge (pronounced "thirty-aught-six" or "thirty-oh-six"), 7.62×63mm in metric notation and called ".30 Gov't '06" by Winchester,〔''Gun Digest Shooter's Guide to Rifles'' Wayne van Zwoll, p 186〕 was introduced to the United States Army in 1906 and later standardized; it remained in use until the early 1980s. The ".30" refers to the caliber of the bullet, and the "06" refers to the year the cartridge was adopted—1906. It replaced the .30-03, 6mm Lee Navy, and .30-40 Krag cartridges. (The .30-40 Krag is also called the .30 U.S., .30 Army, or .30 Government.) The .30-06 remained the U.S. Army's primary rifle and machine gun cartridge for nearly 50 years before being replaced by the 7.62×51mm NATO (commercial .308 Winchester) and 5.56×45mm NATO, both of which remain in current U.S. and NATO service. It remains a very popular sporting round, with ammunition produced by all major manufacturers. ==History== Many European militaries at the turn of the 20th century were in the process of adopting service rounds loaded with pointed spitzer bullets: France in 1898, Germany in 1905, Russia in 1908, and Britain in 1910,〔(【引用サイトリンク】title=Cartridge Specifications and Chronology )〕 so when it was introduced in 1903, the .30-03 service round loaded with a round-nose bullet and achieving a muzzle velocity of was quickly falling behind the ongoing technical evolution.〔(【引用サイトリンク】title=The .30-06 Springfield Cartridge )〕 For these reasons a new case was developed with a slightly shorter neck to fire a spitzer flat-based bullet that had a ballistic coefficient (G1 BC) of approximately 0.405 and achieved a muzzle velocity of and muzzle energy of . It was loaded with Military Rifle (MR) 21 propellant and its maximum range was approximately . The M1903 Springfield rifle, introduced alongside the earlier .30-03 cartridge, was quickly modified to accept the new .30-06 Springfield cartridge, designated by the US military as the M1906. Modifications to the rifle included shortening the barrel at its breech and resizing the chamber, so that the shorter ogive of the new bullet would not have to jump too far to reach the rifling. Other changes included elimination of the troublesome "rod bayonet" of the earlier Springfield rifles. Experience gained in World War I indicated that other nations' machine guns far outclassed American ones in maximum effective range. Additionally, before the widespread employment of light mortars and artillery, long-range machine gun "barrage" or indirect fires were considered important in U.S. infantry tactics.〔George, John (Lt. Col.), ''Shots Fired in Anger'', NRA Press (1981), pp. 402–403〕 For these reasons, in 1926, the Ordnance Corps developed the .30 M1 Ball cartridge loaded with a new Improved Military Rifle (IMR) 1185 propellant and bullet with a 9° boat tail that had a higher ballistic coefficient of roughly 0.494 (G1 BC),〔(【引用サイトリンク】title=M118 History - Sniper Central )〕 that achieved a muzzle velocity of and muzzle energy of . This bullet further reduced air resistance in flight, resulting in less rapid downrange deceleration, less lateral drift caused by crosswinds, and significantly greater supersonic and maximum effective range from machine guns and rifles alike. Its maximum range was approximately .〔(FM 23-10 ''Basic Field Manual: U.S. Rifle Caliber .30, M1903'', 20 September 1943 page 212 )〕 Additionally, a gilding metal jacket was developed that all but eliminated the metal fouling that plagued the earlier M1906 cartridge. Wartime surplus totaled over 2 billion rounds of ammunition. Army regulations called for training use of the oldest ammunition first. As a result, the older .30-06 ammunition was expended for training; stocks of .30 M1 Ball ammunition were allowed to slowly grow until all of the older M1906 ammunition had been fired. By 1936, it was discovered that the maximum range of the .30 M1 Ball ammunition with its boat-tailed spitzer bullets was beyond the safety limitations of many ranges. An emergency order was made to manufacture quantities of ammunition that matched the external ballistics of the earlier M1906 cartridge as soon as possible. A new cartridge was developed in 1938 that was essentially a duplicate of the old M1906 round, but loaded with IMR 4895 propellant and a new flat-based bullet that had a gilding metal jacket and a different lead alloy, and weighed instead of . This 1938 pattern cartridge, the Cartridge, Caliber .30, Ball, M2 achieved a muzzle velocity of and muzzle energy of . Its maximum range was approximately .〔 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「.30-06 Springfield」の詳細全文を読む スポンサード リンク
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