.50 BMG ammo in magazine for the M107 rifle
Attempts are regularly made to create high-precision rifle complexes based on a guided bullet, but so far none of these developments has been able to go beyond the range. Several years ago, the American agency DARPA developed its own version of such a system. The result of the work was the EXACTO guided bullet, which partially confirmed its capabilities at the shooting range.
Years of development
DARPA's EXACTO (Extreme Accuracy Tasked Ordnance) program was launched in 2008. Lockheed Martin and Teledyne Scientific & Imaging were selected as contractors.
As reported, the goal of EXACTO was to find solutions for creating a high-precision bullet with homing or external control. It was required to determine the optimal guidance option, find ways to stabilize and control the bullet in flight, and also solve all layout issues. A promising bullet should have been made in the dimensions of the existing M33 product for the .50 BMG cartridge (12,7x99 mm) for compatibility with a wide range of small arms weapons.
A lot of time was allotted for the development of EXACTO: the finished bullet was planned to be presented by 2015. In general, the work met this deadline, but was soon stopped. On the official DARPA resources, the EXACTO project is now listed as archived.
At one time, DARPA published a computer image of a promising guided bullet and some information about its design. In this case, the remaining data, incl. those of greatest interest were not disclosed. Later, videos from test firing were published, which allowed some conclusions to be drawn.
The only published image of an EXACTO bullet
The EXACTO shooting complex included several main components: a guided bullet in a .50 BMG cartridge, a sniper rifle for this cartridge, as well as fire control tools necessary for precise aiming of weapons and control over the flight of the bullet. Unlike some other projects of this kind, EXACTO provided for the use of serial rifles, which was supposed to simplify further deployment and use.
The exact data on the type of guidance and control methods are still secret. At the same time, there are two main versions in circulation. The first involves the use of a full-fledged optical seeker that receives the reflected signal of the laser illumination. The second offers a simpler solution in the form of a "smart" optoelectronic sight and a bullet with radio command guidance. Published materials and video recordings make the second option more likely.
In this case, it should be considered that DARPA abandoned a full-fledged homing head in favor of remote control, and this greatly simplified and made the bullet cheaper. Thanks to this solution, in the limited volume of the EXACTO bullet, only the power source, the signal receiver, the drives with rudders for control on the trajectory, and the tracer are located.
The complex also includes a new type of optical-electronic sight. It has day and night channels, a laser rangefinder, and is equipped with electronics for processing incoming data and a transmitter for controlling the bullet. During firing, such a sight tracks the bullet along the tracer, calculates its trajectory and issues commands to perform maneuvers to hit the target.
Bullet maneuvers in flight: the tracer demonstrates a sharp change in trajectory
In 2014, in the wake of one of the test events, DARPA reported that a new type of rifle complex in a combat position has the smallest possible dimensions and weight. Thus, the weight of the entire system does not exceed 46 pounds (almost 21 kg). Considering the mass of the current large-caliber rifles, it can be assumed that the "smart" sight for EXACTO weighs no more than 5-6 kg. The available batteries at that time provided work for 14 hours without recharging.
By the beginning of 2014, the new shooting complex was ready for testing. In the winter of 2014, the prototype was delivered to the test site and tested on targets. Information about the conduct of such tests, as well as a video with the flights of bullets, was published only a few months later.
The published video showed how a guided bullet flies in the direction of the target, and at the end of the trajectory it performs sharp maneuvers and hits the target. Tests have clearly shown that the complex is able to compensate for bullet deflections due to incorrect initial guidance or due to the influence of external factors on the trajectory. Unfortunately, the video did not include specific data on the range and accuracy of fire.
It was reported that in 2014, DARPA and Teledyne continued to refine the complex and were preparing for a new stage of testing. The next shooting took place in February 2015 - materials on them were published only in April. This time, the shooting was carried out at a moving target. Both experienced snipers and shooters with insufficient training were involved in the shooting. In all cases, a reliable target hit was ensured.
Bullet flight with guidance. The calculated trajectory and the point of impact during uncontrolled flight are marked in red, the actual
How exactly this shooting looked like was not specified. Apparently, the shooter was supposed to keep the aiming mark on the target, and the automation provided bullet guidance. Thus, the main and most difficult work was performed by electronics, unloading a person.
After April 2015, no new reports of work on EXACTO were published. Known program accomplishments, deadlines, and lack of News became the reason for the emergence of the most interesting versions. In particular, in the foreign media there appeared (and still appear) bold assumptions that the complex was brought to production and operation in the army - but in an atmosphere of secrecy.
However, soon on the official resources of DARPA near the EXACTO program there was a mark “Archived”. For one reason or another, a promising project went to the archive. Work on it has not yet been resumed, although the use of the accumulated experience in new developments cannot be ruled out.
Advantages and disadvantages
The main technical details of EXACTO are still unknown. However, the available data makes it possible to evaluate this project and determine its strengths and weaknesses, as well as find possible reasons for the termination of work.
An obvious advantage of EXACTO, which has been repeatedly confirmed at the shooting range, is the ability to aim a bullet at a target throughout the entire operating range of large-caliber rifles. Combined with the ability to calculate a trajectory from a range of different data, this in theory provides the highest accuracy.
Shooting at a moving target. Red line - calculated trajectory without control, green - actual, provided with guidance
The version of the complex with radio command guidance looks favorably against the background of other similar developments. A bullet with only actuators is simpler and cheaper to create and manufacture than a product with a full-fledged seeker, but due to the "smart" sight it shows at least not the worst characteristics.
The main disadvantage of EXACTO and other systems of this class is the excessive cost. A bullet with special equipment is tens or even hundreds of times more expensive than high-precision sniper cartridges with a “simple” bullet. The high cost drastically limits the use of guided bullets and makes them only an addition to conventional ammunition for specific situations. The same generally applies to the "smart" sight.
The EXACTO product was made in the form factor of a 12,7x99 mm cartridge, but snipers may need ammunition of other calibers and dimensions. The possibility of scaling a guided bullet for cartridges of smaller caliber and power raises fair doubts.
Thus, the result of the EXACTO program was a very interesting and promising high-precision rifle complex. However, its special capabilities and high performance were obtained using not the simplest devices and products, which negatively affected the overall cost. It is very likely that it was precisely because of the unacceptable price that the project was not developed and brought to service. However, this is not surprising. All previous projects of "smart" bullets stopped either because of excessive complexity or because of too high a price. As a result, no army in the world has yet received such ammunition. And the DARPA / Teledyne EXACTO project did not change this situation.