[Back]

Diameter: 5.56mm SCF Arrow missile

Steyr ACR is the U.S. Advanced Combat Rifle (Advanced Combat Rifle) program, one of four kinds of candidates for the program, the adoption of the Aberdeen Proving Ground test the safety and engineering, but also participated in the infantry school at Fort Benning, a field assessment of试验. However, all four programs have not reached the M16A2 rifle shooting a 100% increase compared with the request, ACR program was suspended.

AsACRPlan basic requirement is to increase the hit rate under the pressure of the battlefield, four kinds of candidates are from the new type of ammunition to start the program, a breakthrough in Steyr choice is flechette shells. Arrow missile technology was originally in the 1960s, the U.S. Army TestSPIWPlans once used before, but then the concept of Arrow missile failed. SteyrACRTry Arrow missile technology, and achieved some success.

The missile is nominally 5.56mm caliber, using a simple cylinder-shaped plastic shell. Arrow bullet (or the flying darts) by 4-type wadding positioned completely buried inside the shell. High Carbon Steel Arrow missile diameter of about 1.5mm (0.6 inches) in length and 41mm (1.6 inches) and weighs 0.66 grams (10 grains most of the information is said to exact weight of 9.85 grains). Plastic casings did not pull the shell bottom edge or groove, ring at the end of the fire close to the inner walls of the shell. Arrow bullet weight is very light, compared withSS109Elastic half-light, in the same combat load conditions, each member carrying the ammunition can be multiplied, but the Arrow missile is more important advantage is speed, SteyrACRMuzzle velocity at launch to reach 1450m / s (4750 fps), at 600 meters, the survival rate is still 910m / s (2980 fps), is said to penetrate body armor plates and then existing. And a very flat trajectory, recoil is also low.

Arrow bomb diagram

Steyr Arrow missile and other caliber comparison :1-7 .62 × 51mm NATO; 2-7.62 × 39mm; 3-5.56 × 45mm NATO; 4-4.7mm HK caseless; 5-5.56mm SCF Steyr Arrow type shells

In order to launch this unique cartridges, SteyrACRAlso used a unique design. Nominal barrel diameter is 5.56mm, there is a very slow rifling to make Arrow missile stability, making Arrow the small tail shells on their own to maintain flight stability. The ups and downs bolt is SteyrACRBiggest feature, which is an up and down the activities of an independent chamber, composed of the direct gas system-driven, guided gas piston is a circular structure, set the barrel appearance. The action process is as follows:

First of all, when the chamber is empty when the first drawing machine handle by hand pulling bullets to be shot first. At this time moving down the cylinder position, and magazines with the highest Yifa bombs, guided air piston and piston rod to remain in the final position. When the withholding of trigger, the piston rod and the guide was released gas piston and recoil spring under the pressure to move forward. In this campaign, first of all, by a special hammer hit by bullets from the magazine to the first chamber to move forward, and then in the cam and the cylinder under the action of recoil spring into the chamber with bullets up to a maximum of位置. In the chamber with the barrel into an axis, fixed firing pin hole through the chamber at the top to enter and penetrate the shell wall, thus firing bullets fired at the end of fights. When the Arrow missile through the guide holes, some gunpowder, gas began to foster the mobility of gas piston backward, through the piston rod and the cam, put the empty shells of the chamber with the barrel of a gun magazine on the reduction and re-fall. Then hammer will hit magazines in the next bullets inside the chamber to promote the new bullet into the chamber will remain in the chamber when the air inside the shell of the former top-out, throwing the empty shell casings from the mouth in front of launch. Then continue the shooting circle. In short, after filling the chamber to stay in the bottom position, waiting for the next pinch machines began to rise. Rifle toss at the end of the shell mouth, in the magazine front, this also solved another problem without prop guns - no need to change the direction of throwing the shell will be able to change hands shooting. Because of this particular approach does not require pull-shell ejector hook, so do not need to shell the bottom edge.

SteyrThe structure and principle of ACR

In addition to these features, SteyrACRThe shape is very simple, monolithic polymer shell of the first half like a cylinder, in the middle beneath AUG-style grip, the top of the reference to install the mechanical sights to, but the standard 1.5~3.5 times more variable optical crosshairs. Through-type speed machine has insurance, firing, and three-fat three position rifle-shooting. 24-fat double magazine with translucent plastic, to facilitate observation of magazines I shells volume shooter. SteyrACRDecomposition can be carried out without tools. The absence of care structure, length of only 30.7cm, more thanM16A2Short of 25%. The entire gun with a large number of high-strength composite materials and modular structure, easy maintenance and logistics.

SteyrACRThe main disadvantages, such as the U.S. tests show that it is due to Arrow missile bullet shell strength of the plastic deformation easily lead to changes in chamber pressure. Change in pressure means a change in muzzle velocity and trajectory of change, the accuracy be affected. This, however, by experiment with different materials and combination of methods can be resolved, and it may have been Steyr resolved, are prepared to provide a rifle to the next applicant.

AtACRTest of the weapon works well, but there are two main issues to be resolved. The first Arrow missile plastic shell strength, and easily deformed by external forces, the results of shooting will lead to changes in chamber pressure, the results of the muzzle velocity and ballistic impact of the change, thereby affecting the stability of firing accuracy. This problem can experiment with different combinations of materials and methods to solve, perhaps Steyr may have been resolved, as technical reserves. Another problem is more difficult to solve when the wadding will be spread out in the fly out the barrel, but this is likely to endanger soldiers in the vicinity of, or affixed to shoot shooter may rebound. There is also a secondary issue, that is throwing the location of the shell mouth, if the shooter did not wear gloves, wrist burns may be casings.

SteyrACRBecause of extremely high projectile velocity, the actual range within a very short flight time (hit the 300 meters will take about 0.2 seconds), and the trajectory straight, almost reached the performance of light guns, shooters do not need to think too much ahead of pre-shoot high-volume and ballistic calculations - that is, even if the targets in high-speed movement, as long as the targeting is also very easy to hit. SteyrACRGood lethality and armor-piercing capabilities, but shooting low recoil. But this is still insufficient to achieve the advantages ofM16A2Double hit rate performance, the other three kinds of programs too, soACRPlan was only to give up. Until now, SteyrACRStill remain in the prototype stage, even the pilot did not, so no chance of the above-mentioned problems be resolved.