The LWRCI PSD MKII 6.8x43mm Carbine

The author firing the M6 PSD MKII chambered in 6.8x43mm SPC caliber. Notice the proprietary Magpul magazine designed for optimal feeding of the 6.8mm SPC caliber cartridge. Without a suppressor there is one heck of a muzzle blast!

The First Ever Large Scale Sale of a 6.8x43mm Caliber Rifle to a Military

Back in 2001 a new cartridge concept was thought up by 5th Special Forces Group MSG Steve Holland. He wished to increase the firepower of the Special Operations soldier by providing a much more effective round than the 5.56mm. He felt it lacked the stopping and penetration power needed by a battle rifle. Starting with a .30 Rem cartridge cases, MSG Holland created a wildcat cartridge that would function in an AR/M16 platform rifle and would only require changing of the barrel, bolt and magazine. This prototype cartridge was handed over to the United States Army Marksmanship Unit headed by Troy Lawton. This product would be funded by Remington’s Sean Dwyer, who claimed Remington wanted to do their part in the Global War on Terrorism. Remington began final development of the cartridge in the fall of 2001 using the concept wildcat cartridges made up by MSG Holland which were in effect shortened .30 Rem brass. Auto CAD drawings of the cartridge case were prepared by Cris Murray of the Army Marksmanship Unit. Remington’s final task was to standardize the dimensions. The first production of the new 6.8x43mm Rem SPC cartridge was in 2002 with full production beginning in 2003. Right up to the 2004 time period this cartridge was kept very secretive by all the companies involved. Some of the first rifles were manufactured by David Dunlap of Precision Reflex, Inc. At SHOT Show 2005, many manufactures were quick to produce rifles chambered for the new cartridge before ammunition was even available. However, even after initial release the cartridge was still under development to maximize its potential. SAAMI accepted the new cartridge and some other manufacturers got on board with manufacturing. The finalized 6.8x43mm Rem SPC required a slightly modified chamber than the original, hence the Spec 2 chamber. It was found with the fully optimized ammunition, it was not safe to load it in the original Spec 1 chamber. The primary load was a 115gr Sierra open tip match projectile at a velocity of around 2,650 feet per second. Loads available are from 77 to 135 grains in weight.

Many manufacturers decided to stay with the SAAMI spec chamber which was the original Spec 1. Others went ahead and upgraded to the Spec 2. Ammunition manufacturers did not really want to make a cartridge that would not be safe in some guns that were out there so they mostly stayed with the SAAMI Spec 1 chamber. They could be sure that their ammunition would be safe to shoot in all existing rifles. One company did take on the Spec 2 load and that was Silver State Armory. It would be safe to say that Silver State Armory has done more product development of 6.8x43mm ammunition than anyone out there other than Remington. Their Spec 2 chamber ammo is specifically marked.

Shown is the complete left side of the SIX8-UCIW. Notice the Magpul pistol grip and 6.8x43mm magazine. The rifle is equipped with LWRCK Skirmish folding backup sights.

The path of the 6.8x43mm Rem SPC cartridge is quite disappointing to say the least. USSOCOM looked at it and they were less than thrilled, more than likely not due to its performance capabilities but due to ammunition compatibility. This would also be the introduction of a non-NATO standardized cartridge. Feeding was an issue. Designing a magazine that would fit an M16/M4 lower receiver proved to be a difficult task. The cartridge did get a following in the commercial market. Several companies manufacture rifles in this caliber. The cartridge is ideal for medium game hunting and is quite popular for deer and hog. Few ammunition companies really took it on. Of course Remington offers a good line of ammo. As previously stated Silver State Armory specializes in the 6.8x43mm Rem SPR cartridge offering more loads than any other company. Ammunition is also offered by Hornady, Corbon, Federal, Seller &Bellot, Double Tap and Barrett.

Shown is the right side of the M6 PSD rifle chambered in 6.8mm SPC. This is the configuration of the rifle that went to the Mid-East special operations unit. The only thing missing is the EOTech sight. Notice the ambidextrous bolt catch and selector lever.

Of all the manufacturers of modern military arms, LWRCI has come to be best known for producing military grade rifles chambered in the 6.8x43mm Rem SPR cartridge, releasing their rifle in 2007. The company is known for producing rifles with their proprietary short stroke tapped piston 2that adapted a 6.8 barrel, modified bolt and magazine. Magazines are produced mostly by CProducts Defense and Precision Reflex, Inc. They are now also made by D&H Tactical. In an industry that had pretty much given up on the caliber, LWRCI always believed in its potential and continued to improve their rifles. LWRCI is also in the international market and sells arms throughout the world. Of course their primary sales are all 5.56x45mm and 7.62x51mm. However in 2010, LWRCI met with a special operations group from a Middle Eastern country. Due to contractual agreements they are not at liberty to divulge the name of this unit. This group was looking for a short barreled rifle that packed a heavy punch. LWRCI looked at their requirements and though that this would be ideal for the 6.8x43mm Rem SPC. It was the same size for the most part as a short 5.56mm rifle but packed a lot more punch. The customer was quite interested. LWRCI imported some of their 6.8x43mm rifles in country to do demos. During negotiations LWRCI was told the order would be more than 30,000 weapons. With that kind of number they decided to make a real bold move. They understood the potential feeding issues and the sandy environment could complicate things, so they decided to team up with Magpul and create a proper magazine that would be optimized for the 6.8x43mm Rem SPC cartridge. Logically this means the magazine well must be made wider, which they did. The magazine looks like the familiar PMAG with Maglevel windows and holds 30 rounds.

Shown is the complete left side of the commercially produced SIX8-UCIW . Notice the Magpul pistol grip and 6.8x43mm magazine. The rifle is equipped with LWRCK Skirmish folding backup sights as well as a EOTech holographic sight.

The rifle presented to the Middle Eastern Special Operations unit was the PSD MKII. The rifle has a short telescopic stock which is of LWRCI design. With the stock extended the overall length is 26.73 inches and with the stock closed it is 23.97 inches. The weight of the rifle without a magazine is 6.39 pounds and fully loaded with 30 rounds 7.71 pounds. The barrel is 8.5 inches in length with a flash hider installed to the end. The rifle is selective-fire (Semi- and fully-automatic) and magazine fed. The rifle has quad Mil-Std-1913 rails and comes with LWRCI folding Skirmish back up sights. The rifle is fully ambidextrous with ambi selector, magazine release and bolt catch. Without suppressor the cyclic rate is roughly 700 rounds per minute and with suppressor roughly 1,000 rounds per minute.

Before we delve into the specific features of the rifle there is one very important component to this particular weapon system, the ammunition. Due to the short 8.5 inch barrel there were issues with reliability in adverse conditions. In normal 6.8 loads the port pressure is not at its peak until it is around 8 or so inches. This means the 8.5 inch barrel has low port pressure using standard ammunition. Also the current ammunition is commercial grade, lacking the flash inhibitors in the powder of military grade ammunition. So LWRCI in partnership with ATK Federal went on to develop a round that would be optimal for use in an 8.5 inch barrel. Basically a propellant that was faster burning that would get the port pressures back up to where they would need to be to cycle the rifle reliably. In testing the PSD MKII, this author tested more than 9 different loads. The rifle would only function properly with the specified load. All commercial off the shelf ammunition caused the rifle to short stroke. The load used is called XM68GD. The projectile is a 90 grain Speer Gold Dot projectile with an approximate muzzle velocity of 2420 feet per second and with a muzzle energy of 1181.6 ft lbs. Impressively, the maximum range of the rifle is 500 meters at a point target. Currently all ammunition made for the Middle East customer is ATK. LWRCI ammo has been sourced and tested by Seller & Bellot, Hornady, ATK and Silver State Armory. The PSD MKII is the only rifle that requires this ammunition. The Six8-UCIW which is the current commercial off the shelf rifle will work with standard ammunition. Modifications have been made to the gas system for it to run reliably.

Examining the weapon system the only differentiation between the military PSD MKII and the SIX8-UCIW will be the ammunition compatibility. All other features are the same.

The proprietary Magpul magazine is designed for this weapon system. This magazine was specifically designed to feed the 6.8x43mm cartridge properly and reliably.

Starting with the lower receiver assembly, the rifle is equipped with the LWRCI produced short stock. There are 4 positions. There are two quick-detach mount sockets on the stock, one on each side. The buffer and spring are designed specifically for the 6.8x43mm Rem SPC cartridge. The lower receiver itself is proprietary and not compatible with industry standard receivers. It is manufactured from a 7075-T-6 aircraft grade aluminum forging. The receiver is hard coat anodized as per Mil-Spec to a flat black color. Primary difference is as we mentioned, the magazine. The joint effort LWRCI and Magpul magazine looks like a standard PMag but on steroids. It holds a full 30 rounds and has high visibility orange magazine follower and lock plate. The geometry of the magazine is optimal for this cartridge. So the magazine is wider than the standard magazine. Therefore the receiver is wider. The selector lever is ambidextrous and also made by LWRCI. The lever is easy to grab and manipulate even with gloves. The pistol grip is the very comfortable Magpul MOE. The lower receiver is fully ambidextrous. On the right side, right above the trigger is the ambi bolt catch. It looks the same as the one on the left side and is actuated in the same manner. The magazine catch is in the normal location on the right side of the receiver. On the left side the ambi mag catch is located right behind the catch and is easily manipulated by either a left or right handed shooter. The hammer, trigger, disconnector and automatic sear are all nickel boron coated. The trigger pull is the Mil-Spec 5.5 to 8.5 pounds.

The upper receiver is also manufactured from a 7075 T6 aircraft grade aluminum forging and is proprietary to the PSD MKII 6.8x43mm SPC lower receiver. It has the traditional forward bolt assist, fired cartridge case deflector and ejection port. The handguards have quad Mil-Std-1913 rails. The bottom handguard is held on by a collet over the barrel nut. The top handguard is removed for maintenance of the gas system by two pusher screws. The locking nut itself is non-indexing. The barrel nut is self-locating and guides the operating rod through the upper receiver.

The 8.5 inch barrel is cold hammer forged right at LWRCI. Just at the time the PSD MKII went into production, LWRCI bough their own hammer forge machine. LWRCI has always been very convinced of the benefits offered by the hammer forging process. 41V45 steel-alloy and then treated with NiCorr™ surface conversion technology. This process is deemed superior to using standard chrome plating. The barrel has a 1 turn in 10 inch right hand twist.

The process of drilling and pinning of the gas blocks onto the barrels. LWRCI makes extensive use of custom assembly fixtures throughout their production lines of rifles.

The bolt carrier is a one piece carrier with a machined “tombstone” which is the impact area of the operating rod. The rear of the bolt carrier is flutes which accomplishes two things. One, it deals with and eliminates bolt carrier tilt caused by the off center movement of the bolt carrier in turn caused by the operating rod striking the top of the tombstone. The second is with egression of dirt, fouling and whatever else may find its way into the mechanism. It is nickel boron coated.

The bolt has enhancements over the standard. The extractor, similar to that of the LMT Enhanced bolt has a whale-tale shaped extractor utilizing dual extractor spring with a more aggressive extractor claw. The extractor claw engages more of the surface area of the rim of the cartridge case than the norm. The bolt face fully supports the rear of the cartridge case. This helps prevent case head failure unlike the standard M16/M4 bolt which has a large cutout to allow for insertion of the extractor. This helps to prevent case head failures from high-pressure situations like firing with water in the barrel. The geometry of lugs 1 and 7 has been redesigned to make these lugs much stronger and stress relieved, preventing breakage. Also the face of the bolt has a “crud” groove cut around the perimeter of the inside of the bolt face. This permits crud such as brass shavings, carbon and primer sealant a place to go that will not affect the function of the rifle.

The gas system is made of 4 components. Pinned to the barrel is the gas block/nozzle, then the intermediate rod, piston cup and operating rod are installed. Once the projectile passes the gas port, gas goes up the gas port and into the nozzle, pushing the piston cup, intermediate rod and operating rod rearward. The operating rod gives a hammer-like blow to the tombstone on the bolt carrier driving the bolt carrier to the rear. The bolt unlocks and the extraction and ejection process commence. The spring on the operating rod returns the operating rod, intermediate rod and piston cup forward ready for the next shot. Hot gasses escape at the front of the gas system. This eliminates hot and dirty fouling entering the carrier group. The bolt carrier remains cool as well.

A box of receivers ready to assemble into PSD MKII carbines for the Middle Eastern customer. Notice the use of UID code labeling. These receivers are fully ambidextrous.

For the Middle East contract the PSD MK11 was put through a gamut of testing. This includes mud, sand, water, salt spray and temperature extremes. The gun was tested up to 40,000 rounds. Keep in mind the Mil-Spec acceptance testing for the M4 carbine is but 6,000 rounds. The first rifles were delivered in 2012/13. This sale is a landmark in the history of the 6.8x43mm SPC cartridge. It documented the first large sale order (30,000+ rifles) in the industry. The cartridge was designed by MSG Holland as a Special Forces cartridge. Although it never saw US military service, it was adopted abroad. The customer appears to be very pleased with the performance of the rifle. They possess the most firepower of any military for a rifle that size. For the desert environment, the 500 yard range is also a plus. Part of the rifle’s requirement is that it shoots sub MOA at 100 meters. This is an excellent example of quality of the system (rifle and ammunition), especially for an 8.5 inch barrel. Every rifle sold to the customer is ready to install a sound suppressor as well.

The author was provided with 500 rounds of the Federal XM68 ammunition from LWRCI along with one PSD MK11 and one SIX8 with a 16 inch barrel. Also brought to the range was 6.8mm Rem SPC ammunition manufactured by Silver State Armory, Remington and Hornady. Projectile ranged from 90 to 115gr. The range was limited to 25 yards so accuracy testing was limited. The optic chosen was the EOTech holographic sight which is the one provided with the PSD MKII to the middle eastern customer. With the PSD MKII, the accuracy was clover-leafed at 25 yards which was expected with the XM68 ammunition. All other ammunition tested in the PSD MKII did not cycle properly. The rifle would continuously short stroke. This was expected due to the entire reasoning around the development of the XM68 ammunition in that short 8.5 inch barrel. When the 16 inch Six8 barrel was installed on the lower, all ammunition brought functioned flawlessly including the XM68. Between the 8.5 and 16 inch barrels more than 800 rounds were fired. I have to say, this author has tested 6.8x43mm SPC rifles in the past and has never experienced this type of reliability. With all the standard mags tested they just never were combat reliable. The LWRCI rifle using the proper designed PMag for this cartridge worked without issues. LWRCI really took a gamble on designing a “Not industry standard” receiver platform to optimize the use of this caliber and it certainly paid off. This author is quite surprised the industry has not followed in building rifles in this caliber.

The LWRCI sale to the Middle East is a true milestone in the book of the 6.8x43mm SPC cartridge. Is this the ideal military caliber? Could be. NATO standardization will always be a major factor in anything adopted. This may always have and continue to prevent this cartridge from ever going prime time. Sometimes being better is just not good enough. You always have the politics that get in the way. For special operations units who can request and purchase their own gear, this is a very viable option for a high performance firearm. This sale to this undisclosed Middle East country is a perfect example of this. American hunter, target shooter and enthusiasts use this caliber every day. No question that the caliber has its following.

Assembly of the barrel, flash suppressor and piston system.
The bolt of the PSD MKII chambered in 6.8x45mm Rem SPC. Notice the whale tail shaped enhanced extractor as well as the two extractor springs.
The nickel boron coated bolt carrier group of the PSD MKII chambered in 6.8x45mm Rem SPC. Notice the carrier itself is one piece and the flutes on the rear of the carrier.
This 6is how each and every of the rifles shipped to the Middle Eastern customer was packed. Over this station was a video camera which took a photo of each completed box. This was if something was missing in the box, LWRCI could look up the serial number and pull up the picture to verify if the product was missing at the time packing.