Remington created a larger cartridge called the ".222 Special", which was loaded with DuPont IMR4475 powder. Stoner contacted both Winchester and Remington about increasing the case capacity. But testing showed chamber pressures to be excessively high. During a public demonstration the round successfully penetrated the U.S. Testing was done with a Remington 722 rifle with a 22-inch Apex barrel. He used DuPont IMR4198, IMR3031, and an Olin powder to work up loads. Robert Hutton (technical editor of Guns & Ammo magazine) started development of a powder load to reach the 3,300 ft/s (1,006 m/s) goal. Using a ballistic calculator, they determined that a 55-grain bullet would have to be fired at 3,300 ft/s (1,006 m/s) to achieve the 500-yard performance necessary. Stoner and Sierra Bullet's Frank Snow began work on the. As a result, CONARC ordered rifles to test. In May 1957 Stoner gave a live-fire demonstration of the prototype of the AR-15 for General Willard G. Wyman, Commander-in-Chief of CONARC. Harvey was ordered to cease all work on the SCHV to avoid any competition of resources.Įugene Stoner of Armalite (a division of Fairchild Industries) had been advised to produce a scaled-down version of the 7.62mm AR-10 design. Concurrently with the SCHV project, Springfield Armory was developing a 7.62mm rifle. 222 Remington cartridge case to meet the requirements. Springfield Armory's Earle Harvey lengthened the. Accuracy and ballistics equal to M2 ball ammunition (.Penetration of US steel helmet through one side at 500 yards.Select fire for both semi-automatic and fully automatic use.Bullet exceeding supersonic speed at 500 yards.Test barrel length: 508 mm (20.0 in) Source(s): NATO EPVAT testing, QuickLOAD, SAAMI, C.I.P. NATO, Japan, South Korea, Taiwan, Australia, other major non-NATO allies 5.56×45mm NATO with measurement, left to right: projectile, empty case, complete round with projectile in case