[quote|MIKLE, 08.03.2004 18:19:09 :]1. Наоборт спасибо. А то савсем забыл. Так хотьесть стимул повспоминать. Статейки интересные. Буду читать.
2. Ну да ладно. у них новых образцов и так хватает. А .408 ещё обкатать надо. Одно дело новый ствол по старый патрон, а тут новый патрон да не один... Хотя в перспективе если вместо 5.56, 7.62 и 12.7 перейти на новые .2хх и .408-заманчиво выглядит...[/quote]
1.Я всегда рад служить.
2. Ну тут еще новый калибр нарисовался 6.5 мм Грендел, разработанный Александром Армс в Радфорд Арми Арсенале.( Alexander Arms of Radford Army Arsenal)
Армия с интересом присматривается к нему,так как он был специально разработан для АR платформы.
"The 6.5 Grendel is an evolution of the 6.5mm PPC optimized to seat 107-130 grain match bullets at an overall loaded cartridge length of 2.255 inches. Case length was kept to 39mm or 1.505 inches as in the original PPC. Studies found that using a slightly longer case would lead to seating bullets deep in the case and would at the very minimum limit the bullets usable to only a few offerings. The case body is perfect in length to stabilize the cartridge in the magazine and prevent tipping without having to resort to special and normally jam prone followers. In addition, the case diameter is the maximum dimensions that allow a double column feed.
Powders suitable for this case size typically are close to 100% load density created optimum conditions for uniform combustion. In developing production ammunition and measuring the internal pressures when firing such loads, the instruments report back mean average pressures in the range of 42,000 psi. Given that the rifle will safely operate and pass long-term fatigue tests at pressures of 45,000 psi, the internal pressures for production ammunition are mild to the delight and relief of both engineers and insurance agents. More impressive is that at these mild pressures, a consistent muzzle velocity of 2600 fps is achieved with a 123-grain bullet. Shoot a string of 10 rounds however and something magical happens. Velocity figures with corresponding pressure curves do not change shot to shot. Typically, a 10 shot sting has a maximum spread in the low single digits and the bullets strikes form a single clean hole in the target. For the rifle itself the steady pressure allows the gas operation to be finely tuned such that the bolt carrier impulse is identical shot to shot and the parts move at close to optimum design speed. Ejection patterns are consistent and the whole operations cycle becomes reliable and repeatable as the parts are always doing the same thing at the same speed.
One of the great benefits of 6.5mm caliber is the high coefficients of drag (Cd) for given bullet weights making them ideal for long range shooting. The 6.5 Grendel is no exception.
The 123-grain Lapua Scenar with a ballistic coefficient of .547 launched at modest 2600 fps muzzle velocity delivers outstanding long range performance out to 1200 yards. Accuracy levels were impressive with test rifles forming single digit groups at 1,000 yards and at 600 yards, tennis ball sized targets are easy prey.
In ballistic gelatin tests, the Lapua 108 grain Scenar launched at a muzzle velocity of 2750 fps penetrated 22” of gelatin with a .43” diameter and 64 % weight retention at a distance of 300 yards. As a more casual test, the Lapua 108 grains bullet consistently sliced through 4” pine posts at 900 yards.
In the interest of game hunting, the 120-grain Nosler Ballistic tip at a 2600 fps muzzle velocity was tested in ballistic gelatin. This bullet penetrated 18” and expanded to .51” diameter with 75 % weight retention at a distance of 300 yards. The recovered bullet exhibited perfect mushrooming with no core separation."