Another incredible Rifle and “Bullet”

The folks at the Advanced Weapons Research Center (AWRC) at the Aberdeen Test Center have done it again.  I was recently asked to help design a scope for a new rifle and bullet combination that is unlike anything ever seen before.

Imagine this:

A normal size long barrel sniper rifle shooting a common cartridge size bullet that leaves the barrel at an incredible 15,437 feet per second (over 10,000 MPH) but has no more recoil than an M-14.  The bullet has the flattest trajectory of any weapon ever made and is lethal out to a range of more than 12 miles.  The bullet is also almost completely unaffected by cross winds, Despite these incredible speeds and ranges, the bullet is rock solid stable over its entire flight including while passing transonic speeds.

As you might imagine, using some kind of enhanced aiming device is essential to remove the human errors from the equation but much of the credit for a stable trajectory comes from the gun and bullet design.  To begin with, it is a smooth bore rifle – which virtually eliminates errors like spindrift, Magnus effect and Poisson affect.

The barrel also is oddly shaped.  It uses a specially designed De Laval nozzle about half way down the barrel.  This constricts the barrel and then expands it.  The result is that the gases from the gunpowder create an intense high pressure point that accelerates the bullet by more than 40 times.

The bullet is a sabot round but unlike any you have seen before.  It is two stages.  The actual penetrator is a needle about as long and thick as a pencil lead and about half the weight of a dime (about 1.5 grams).  The rear end of it is slightly expanded into a grooved bulb that acts as both the receiver for the center of pressure and the grooves form subtle stabilizing fins that also impart a stabilizing spin to the bullet.  Toward the pointed end is the center of gravity, like an arrow, so that it remains stable even at very high velocities. The bullet is essentially a dart that is a specially tooled hardened steel spear with integrated fins

The base sabot pad receives the casing powder blast and applies the center of pressure to the rear of the base-pad of the first stage sabot.  The bullet accelerates down the barrel until it reaches the De Laval nozzle.  There, the constricting barrel disintegrates the first sabot stage and passes the much smaller second stage spindle type sabot through the De Laval Nozzle where it is accelerated before leaving the barrel.   The dart-bullet is moving at about 15,400 fps at the muzzle.  The grooved bulb end gives it a spin that is just enough to maintain stability without creating the usual spin errors.  It also keeps the center of pressure and force directly behind the center of gravity – keeping it stable.  This design results in a Ballistic Coefficient of about 39.7.

You might recognize this design by its similarity to other sabot rounds used for tank armor penetrators or sabot flechettes but this is different.  It optimizes all aspects of the design to achieve the highest possible velocity.   The velocity boost provided by the De Laval nozzle in the barrel plus the specially selected gun powder pushing a 10 gram bullet down a 37” barrel gives the dart a super accurate flat trajectory and the longest range for any small arms weapon.

Of course, such small projectile, range and speed introduce obvious problems.  The first is the lethality of such a small penetrator.  That is solved by the unique design of the dart.  The tip of the dart is shaped like a long tapered needle, however, it hides a hollow cavity (filled with sodium and phosphorus).  The thin metal walls of the tip are aerodynamically shaped to withstand the high velocity wind forces but are very fragile to forces from other directions.  Similar to the extraordinary strength shown by an egg when squeezed on the ends but it easily crumbles when squeezed from the sides.  The hollow cavity dart is specifically designed to collapse and peel outward when it penetrates even the slightest resistance.  When that happens, it exposes the small tube of sodium and phosphorus that reacts with air and/or any liquid to rapidly cause the disintegration of the dart.

The dart design is even more complex than just being a hollow-cavity spear.  Beginning about two inches back from the hardened steel tip, the shaft and tail of the dart is made in 5 thin layers from the outside to the middle and in four longitudinal sections.  These layers are made of high-tension spring steel that is bound by a softer and more pliable metallic-bonding agent.   At the end of the dart, the slight bulge that makes up the flight stabilizing tail is hardened to bind and hold all these layers.  Just in front of this bulge, is the hollow cavity containing the sodium and phosphorus.  The net effect of this design is that upon encountering any resistance, the dart will peel from the front to the back like a banana and the peeled sections will immediately curl and flare outward from the dart.  This takes the streamlined dart from a fast moving shaft to a 5 or 6 inch diameter ball of razor sharp hardened steel coils that can expand and expend all of its energy in .0005 seconds and over a distance of less than 9 inches.

During testing, it was found that despite hitting a bullet resistant vest, the dart took nearly the same distance and time to create its deformed ball meaning that it penetrated the vest before the deformation started.  The effect on animal test targets was incredible.  A cow was shot from 4,000 yards and the point of entry was 2.7 mm in diameter and the dart did not exit the animal but upon autopsy, the cow was found to have a cavity of nearly 16 inches in diameter that was effectively mush.  When fired at a human sized model made of ballistic jell, the exit wound was 9 inches in diameter.

The next problem was the speed of the bullet.  This speed creates a projectile that remains supersonic out to a range of more than 12,000 meters (7+ miles).  It can travel that distance in less than 4 seconds.  Such speeds resolve a number of problems and might have introduced errors.  Air fraction heat was one that had to be dealt with.  The dart can heat up to 160 degrees C during flight but this was used to advantage.  The bonding agent used in the sectional makeup of the dart was designed to be hard enough to withstand the heat and blast of firing the weapon but had to be fragile enough to expand when it hits a target.  The air fraction heat partially softens this bonding agent and the job is completed by the initial penetration of the target – explaining why it can penetrate the bullet-resistant vests but still expand in soft tissue.  The sodium and phosphorus is added just to ensure that the maximum energy is dissipated in the target.

The final problem is aiming a weapon that can accurately shoot farther than the shooter can see.  This was solved by integrating this weapon into the Digital Rifle System (DRS) described in an earlier report on this blog.  The DRS-192B, which is now deployed, uses the MDR-192B rifle as its basic weapon component.  In the case of this sabot-firing rifle, the same basic rifle is used but has been modified to handle this sabot round and uses a modified barrel.  These relatively minor modifications can be made in the field making the MDR192S out of the MDR192B.    In both cases, it uses the basic DRS192 system to coordinate aim point using advanced video camera sights (VCS), AIR (autonomous information recon) devices and, of course, the central processing and imaging computer.

The sabot firing MDR192S, integrated into the DRS192 creates a weapon system that can actually shoot over the horizon of the shooter.  The computers can aim the rifle so accurately that during the testing at Aberdeen and in Colorado, we were able to deliver kill shots at targets at ranges of 11.2 and 12.7 miles.  Accuracy improved markedly at ranges of less than 9 miles to where a kill shot was made in 19 of 25 shots.  Refinements in the AIR’s and VCS’s should improve accuracy in the next model.

A few curious aspects of this weapon.  At the target end of the trajectory, the impact is almost completely silent.  It sounds like someone rapped their knuckles on the table.  The sound from the muzzle of the rifle arrives as much as 1 minute later and is often so weak that it is not associated with the bullet strike.

The enhanced DRS system allows the shooter to be within visual sight of the target while the weapon is located up to 12 miles away.  The use of high terrain for weapon placement while using a visual spotter makes for a combination that is nearly impossible to locate or defend against.

DARPA is already working on an explosive tipped dart that can be used against people, vehicles, aircraft and communications equipment.

Getting shot at by the US military is getting down right dangerous.

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