Weapon Name- SABR 6.5mm
Round Type- 6.5mm x 45mm AUG
Over-all length- 28-30 inches
Barrel length- 20.5 inches
Weight- 7.2 lb
Rate of Fire- 600 RPM
Feed Mechanism- Detachable Box Magazine
Round Capacity- 30, 40, 75
Effective Range- 600 meters
Range- 1000 meters
Accuracy- 1.1 MOA, .8 MOA
Accessories- Picatinny Rails
Quick switch firing mechanism-
Scope/Sights- Integrated carrying handle and iron sight
Muzzle Velocity- 850 m/s, 7.15 gram (2600 joules)
Firing System- Lever delayed gas-assisted blowback
Miscellaneous/electronic information- The weapon utilizes a lever delayed blowback firing system, firing a 6.5mm x 45mm round similar in performance to the 6.5mm Grendel.
Basic Information
The weapon utilizes a lever delayed blowback firing system, firing the 6.5mm x 45mm round similar in performance to the 6.5mm Grendel. Despite being called the 6.5mm x 45mm AUG, the bullet diameter of the cartridge is only 6.2mm (like how he .357 magnum and .38 special fire the same round, despite the different nomenclature). The round utilizes a slightly longer, aluminum cased 110 grain (7.15 gram) 6mm round traveling at 850 m/s and generating 2600 joules, being around about as powerful than a standard 6.5mm grendel, which has a 123 grain (8 gram) cartridge generating 2600 joules. The original purpose for shifting to the 6.5mm AUG cartridge over the 6.5mm Grendel was to increase the reliability in feeding by using a slightly different and longer case, reducing the barrel wear by lengthening the neck of the case, and allowing for slightly longer bullets with more gunpowder to be used, which increases the aerodynamics of the cartridge. While the 6mm rounds have a very high BC and good aerodynamics (with a G1 BC of .617), the round is very long and thus necessitates a much longer case than even the 6.5mm Grendel uses. The unusually long cartridge is better for loading in semiautomatic weapons, but is 2.5 inches long versus approximately 2.25 inch for a standard 5.56mm or 6.5mm Grendel, and thus cannot use the same magazines. The newer cartridge case was designed from the ground up to feed reliably in semiautomatic and fully automatic weapons, with a slight taper similar to that of the 7.62mm x 39mm and an enlarged casehead to help with feeding and extracting. This larger case ordinarily would be heavier than a standard 7.62mm x 39mm or 5.56mm x 45mm cartridge (6.15 grams), however it utilizes a polymer coated aluminum case, which is about 3 times lighter than a standard 5.56mm case and prevents the overheating problems typically associated with aluminum rounds. Based on the 6mm SAW concept, the weapon utilizes a very high BC round in a lightweight aluminum case in order to reduce weight of the round, while still maintaining the high power and range of the 6mm round. The round can be used in smaller, lighter weight weapons roughly the same size as 5.56mm weapons, and produces similar felt recoil, being easily fired from a light machine gun or assault rifle. Unlike a full sized rifle round like the .308 the recoil is manageable in fully automatic fire and short bursts, and unlike the 5.56mm it has a very high BC which gives it the range and armor penetration of the more powerful .308, despite having lower initial muzzle energy. This round exists in a middle ground between both of these rounds, serving as a true intermediate cartridge between the two. The round is more powerful than a 5.56mm and penetrates armor slightly better, being more powerful and having a longer range, and also penetrating common barriers that the 5.56mm cannot (such as glass a 45 degree angle).
The weapon itself was largely designed around the cartridge, which has a number of notable improvements over the previous 6mm SAW cartridge. The cartridge is roughly the same weight as the 6MM saw, being slightly heavier with a 7.15 gram round vs. a 6.8 gram of the previous round, and thus is only about 11.75 grams in weight in comparison to 10.6 grams in weight (lighter than a standard 5.56mm x 45mm NATO at 12.5 grams, and a 7.62mm NATO at 25.5 grams), or 7.15 grams for the bullet, 2.2 grams for the powder, and 2.4 grams for the case. Despite being larger and more powerful than a 5.56mm, roughly the same amount of ammunition can be carried in terms of weight, and roughly twice as much can be carried as the 7.62mm NATO. The very aerodynamic and long, high BC 110 grain (7.15 gram) cartridge is a large part of the weapon's design, having a G1 ballistic coefficient or .617, which gives it incredible aerodynamics and thus the ability to reach out to the same ranges as the much larger 7.62mm NATO round, despite being smaller, fullfilling a niche role that places in between these rounds in terms of performance. The round is also slightly more aerodynamic than the 6.5mm Grendel with a slightly flatter trajectory, but more or less possesses similar performance. The round has very good long range performance, possessing more energy at 300 yards (1800 joules) than the 5.56mm at the muzzle, 1300 joules at 600 yards, more energy than a .357 magnum at 800 yards (1000 joules), and roughly the same energy as a standard handgun round while also still being supersonic to 1500 yards (400 joules). The 6mm has more energy than a 7.62mm NATO at 500-600 yards and beyond, meaning it actually performs better at these ranges despite the low initial muzzle energy. This incredible long range performance out does even the .308, and is vastly superior to the 5.56mm, which drops off in power substantially at 300 yards. Despite being referred to as a 6.5mm round, it is actually only 6.2mm in diameter, much like how the .44 magnum is actually .424 in diameter, or the .38 special is actually .357. This nomenclature difference can cause some confusion for new shooters, but it does not share the same rounds as the 6.5mm Grendel or other 6.5mm weapons.
Part of the reason for the switch was to have a round that performed as well as the 7.62mm NATO at long ranges but could be used in a 5.56mm sized rifle and shared between the LMG and assault rifles of the squad, and part of the reason was to fill the gap left by the 5.56mm's poor terminal performance. While the 5.56mm is adequate at close range, past 300 yards the round suffers dramatically, losing most of it's power and accuracy and additionally failing to tumble and fragment under 760 m/s. According to reports by the U.S. military, the 5.56mm failed to perform as well as the military was hoping at ranges of 300-600 meters, and has roughly 50% of engagements in Iraq and Afghanistan were between 300-900 meters, this became a pertinent issue for the U.S. military. The M14, a weapon chambered in the 7.62mm NATO, was reintroduced, but due to it's heavier weight, poorer maneuverability and lack of standardization with the 5.56mm, created issues being integrated in to the squad. Instead with the SABR 6.5mm AUG, the round can now reach these ranges with relatively little problem, allowing every soldier to be potentially be a marksmen, and the machine gunner to suppress out to long ranges, the same as the 7.62mm NATO cartridge. The 6mm AUG round has more energy than the 7.62mm NATO at 600 yards, and a flatter trajectory, reaching a maximum height of 3 foot above the target along a 600 yard trajectory. At 1000 yards the round only reaches a maximum height of 8 feet, which is less than the 7.62mm NATO at 850 yards with 10 feet, or the 7.62mm NATO sniper round of 10 feet at 1000 yards. However, the weapon drops off rapidly after this, increasing the maximum height of the cartridge to 12 feet at 1200 yards. Compared to the 6mm SAW cartridge, it uses a heavier bullet and has slightly more power, utilizing .25-45 sharp gun powder and 35 grains of powder instead. Using the same powder weight of 28.5 grains, the weapon possesses 2350 joules vs. 1800 for the 5.56mm, while maintaining the same pressure and recoil level. By using the same powder in the 6mm AUG, the cartridge is much smaller than it's power would otherwise suggest, and it allows for a cooler, cleaner burn. The aluminum case of the 6mm AUG also differs from the 6mm SAW, in that it has a silicon dioxide coating to prevent oxidation of the aluminum, a silicon lubricant to help lubricate the weapon and prevent fires from occurring, and a polymer outer coating of the same type of polymer rounds to prevent the aluminum from coming in to contact with the receiver. As the previous 6mm SAW round had a tendency to catch on fire and overheat, these measures not only prevent heat up build up but also reducing the galling and abrasion from the previous aluminum rounds, thus preventing the metal dust build up that had a tendency to catch fire. The polymer also serves as an insulator, reducing heat build up in the rifle and protecting it from overheating to an extent. The weapon does not need to be cleaned as often, producing less fouling than typical gun powder, having almost no galling and metallic residue from the cartridge (being polymer coated instead), and using a non-flammable, non-toxic silicone lubricant that helps cool down the rifle and that re-oils the rifle as each new round is loaded.
The weapon uses a detachable polygonal cobalt chrome gain twist "flow formed" 3 groove 1:7 inch (1 complete turn in 1 in 7 inches / 180 mm) right hand turn barrel; the barrel is made of an alloy that contains more than 50 percent cobalt. The barrel is roughly 13% heavier than standard steel barrels, but is more erosion and corrosion-resistant and is designed to retain high strength during long-term exposure to high temperatures. Cobalt alloys are frequently used in the aerospace industry, such as the hot-gas section of turbine engines. A proof of concept M240 7.62mm x 51mm NATO barrel, in practice, had 24,000 rounds test-fired through it, causing it to reach temperatures of 1,100 degrees, without failure. A steel barrel would have failed under such treatment. The gain twist not only enhances the accuracy of the weapon, but also dramatically increases it's life. As the first 4 inches and last 4 inches of the barrel receive the greatest wear, the gain twist allows a more gradual application of the rifling, thus providing less friction to the bullet and the barrel, which both increases accuracy and durability, as well as the velocity of the bullet. The barrel itself, combined with polygonal rifling, is extremely durable, and has a minimum 30,000 round barrel life, although it is possible to extend this or get use out of the rifle after the minimum is reached. In addition to this, the barrel is cryogenically treated, making it harder and thus slightly more durable. All of this combined gives the barrel a typical 1.1 MOA accuracy, or .8 MOA if a slightly modified marksmen barrel is used instead, which is roughly on par with a sniper rifle. The barrel is accurate, durable, and corrosion resistant, importantly also having good heat resistance. The barrel is detachable in a mechanism similar to the Tavor, but uses locking lugs on both sides of the barrel, and is optionally quick detachable. Quick-detachable barrels, like on the Steyr Aug, are generally inaccurate, possessing around 4.5 MOA, which etheir requires precision made parts (like on a machine gun) to compensate or poor accuracy in order to operate. As a result, like the Tavor it has a locking mechanism to keep barrel tight within the weapon, but it also can be fitted in the weapon without these tightening mechanisms. This gives the option of having a quick-detachable barrel or a slow detachable barrel, thus allowing for the ability to swap barrels quickly in combat with LMG or SAW variants of the weapon, but be tightened if better accuracy (such as with a Marksmen weapon) is desired.
The weapon itself uses a rather simple and rudimentary lever-delayed blowback system like in the FAMAS or TKB-517, that is reliable and has few moving parts, as well as being accurate with no drill port in the barrel and no moving piston needed to operate the weapon. This increases the simplicity of the rifle's function, making it more reliable and easier to maintain and clean, while also increasing the accuracy somewhat, and well beyond that of most long stroke gas pistons. With no gas piston, there is less fouling in the rifle, with most of it being vented out the barrel, and thus is does not need to be cleaned as often. While roughly as reliable as an Ak-47 and more accurate, the weapon unfortunately suffers from a tendency to produce very high rates of fire, up to 1200 RPM. This is bad for an infantry firearm for several reasons, including a tendency for the weapon to overheat and wear out exponentially quicker (wearing out about 3 times faster despite being only twice as fast as a 600 RPM weapons), higher recoil, and a tendency for soldiers to run out of ammunition faster, making ammunition conservation more difficult. As hitting the same target 3 times as opposed to 6 times results in very little difference in take-down power, this extra ammunition is essentially wasted, and thus better conserved at lower rates of fire. To mitigate this somewhat, the weapon has a very stiff, dual-spring recoil rod, a hydraulic recoil buffer, recoil buffer similar to that in the HK45, and a muzzlebreak. The muzzlebreak on top of reducing the felt recoil by about 40% also acts as a spigot or muzzle booster, pumping small amounts of gases back down the barrel to help assist in the backwards cyclic action of the weapon. In this way the weapon functions more like a gas-assisted blowback operation weapon, which is more reliable and has a lower rate of fire of nearly 600 RPM. These measures also help reduce the recoil of the weapon and make the operation more smooth, which on top of the nitrided parts keeps the felt recoil of the weapon down to a minimum. The weapon also utilizes front and rear locking helical locking lugs like in the FR F2, which helps makes the weapon's operation smoother and lighter, which decreases the weapon's felt recoil and friction (and resultingly heat) in the weapon, as well as improving the accuracy somewhat. The weapon also has muzzle break that not only helps to dampen barrel vibrations and that's muzzle ports matches the grooves the rifling in the barrel which helps limit distortion to the projectile as it's leaving the barrel, the accuracy is enhanced further.
The muzzlebreak helps reduce the felt recoil by about 40%, while the HK45 style recoil buffer reduces it by approximately 30%. Both of this measures reduce the peak recoil force of the weapon, from about 6000 newtons to 600, which makes the felt recoil smooth and light, and also reduces it to a more tolerable level for the average shooter in rapid fire. Combined with the hydraulic recoil buffer housed within the stock and recoil spring, the recoil of the weapon is extremely controllable, and slightly lighter than a 5.56mm weapon. This helps the weapon maintain controllability under high volumes of fire. Due to the barrel and lack of a piston mechanism, the weapon can handle a much higher temperature than most firearms, also possessing an aluminum cased round that absorbs most of the heat but due to the polymer case does not transfer is to the weapon, and this in turn helps keep the weapon cool when operating, giving it an incredibly high 80-100 RPM it can handle before overheating. With an optionally quick detachable barrel, the weapon can serve easily as a light machine gun, however the magazine capacities are prohibitively small for these purposes, with the only reliable drum magazine holding 75 rounds. Nonetheless it is a very effective rifle in nearly every role, with the range of a sniper rifle, rate of fire of a light machine gun, and versatility of an assault rifle. The weapon has 2 inches of adjustability in the stock, which allows it to fit to the shoulder and gear of an individual soldier, but is much stiffer than most adjustable stocks, serving as a good platform for accuracy. The weapon possesses an ambidextrous 3-position safety and a non-reciprocating bolt handle on the top of the firearm, as well as an adjustable cheek weld with an additional kevlar pad underneath it to protect the soldier's face in case of a catastrophic malfunction in the firearm. The trigger is 6.5 pounds, relatively light for a bullpup and crisp, using an incredibly smooth and deburred trigger system to reduce the pull weight and make it easier to rapid fire with. The weapon performs remarkably well out to 600 yards, being far superior to the 5.56mm in terms of power and barrier penetration, as well as the 7.62mm NATO round. The smaller diameter bullet with high energy can penetrate armor better than the 5.56mm or 7.62mm at 600 and 1000 yards, and does better than the 5.56mm even under 100 yards. The weapon has 45% more power than a 5.56mm and 30% more power than an Ak-47 at the muzzle, with a round roughly the same size as an Ak-47, giving it good barrier penetration and stopping power. The round shares commonality with the machine gun of the squad, thus reducing logistics problems for the military.
