Tag Archives: 300blk

The Desert Tech MDRX

Advancing technologies have made every part of the firearm and shooting industry better, with new materials, better production equipment, and a growing competitive market all driving forward it is no wonder that so many new and exciting products are available today. Desert Tech has been pushing those limits since its inception in 2007, and this year they have released another great product that follows the Desert Tech adage Tomorrow’s Weapons.

The MDRX is the next generation rifle from Desert Tech, it builds on the already popular MDR rifle they released in 2016. The MDRX is a short-stroke piston operated semi-automatic bullpup, for those who don’t know already, a bullpup is a rifle configured such that the action, magazine, and firing mechanics are all located behind the trigger. The purpose of this design gives the MDRX a shorter overall length than conventional rifles of the same barrel length. When you add in the other additional features of the MDRX the difference becomes even more apparent.

Features
All Desert Tech rifles are designed with modularity in mind, and as such, they are all available as multi-caliber chassis and barrel combinations. The MDRX shares that same heritage, as it stands at the moment it is available in four different calibers from the factory; 223 Wylde, 308 Win, 300 BLK, and 6.5CM. All four of these barrel conversion kits can be interchanged in the same chassis, making the MDRX one of the few modern sporting rifles to accept both large and small frame calibers. All this from an SBR sized weapon without the stamp.
Being a semi-auto bullpup adds some challenges when it comes to universality, these challenges were overcome with ingenuity. The MDRX is completely ambidextrous, all of its controls are mirrored on both sides of the rifle for both right and left-handed shooters. In addition to the ambi controls, the rifle has a forward ejecting system that sends spent brass casing forward away from the shooter. Previous bullpup designs eject brass to the right side, which in a bullpup is a bad thing if you are left-handed. The MDRX can be fired from the right or left side with no concern of catching hot brass to your face. And if you are a dedicated left-hand shooter, you can swap ejection from forward right to forward left in just a few seconds.
The MDRX comes standard with a compensator made by Desert Tech called The Ratchet, the compensators are caliber specific to provide the best performance in recoil reduction and to stop muzzle rise.
One of the major challenges with bullpups is creating a good clean trigger pull, this is due to the linkage required to connect trigger shoe to the sear pack. This is another challenge that was overcome with design ingenuity, and the resulting trigger feel of the MDRX is widely accepted as great. Of the many people who have pulled the trigger on an MDRX, the common consensus is that it is a good trigger, not just for a bullpup, but a good trigger period.
The MDRX has a six-position adjustable gas valve allowing the operator to tune the rifle to whatever ammunition they might use, as well as use the rifle with a suppressor and a lower gas setting.
The MDRX’s aluminum/polymer chassis construction features full-length upper Picatinny rail, M-LOK slots for accessories and flush-mounted QD sling cups on the rear of the receiver. It is also designed to accept most AR-15 style magazines, and for large frame calibers, it uses SR-25 pattern mags. The rifle ships with caliber appropriate P-mags from Magpul.
The various caliber conversions for the MDRX feature popular twist rates, and standard barrel thread for adding muzzle accouterments. There are also both sixteen-inch, and twenty-inch barrels available in several of the assorted calibers, giving shooters different performance options. And with different barrel lengths, there are two different handguard lengths to go along.
The ambidextrous charging handles of the MDRX are non-reciprocating, they are normally locked to the front in a spring-loaded detent. They can also be locked to the rear by pulling them back and up, the release is as simple as slapping either of the handles down, and the bolt carrier closes into battery. The gun locks open upon firing the last shot from the magazine, the bolt release is centrally located right behind the magwell. This allows for very quick reloads by simply extending the thumb when seating a fresh magazine, thus closing the bolt on a fresh round. This actually can make reloading faster than most AR-style rifles due to fewer steps in the reload process.
The forward ejection system is perhaps the most curious of all the MDRX’s features. The open-faced bolt extracts the spent case and carries it to the rear, as the carrier travels it engages the ejector with a dovetail lug on either side. The momentum of the carrier then pulls the scissor-like ejector out, and it swipes across the open bolt face pushing the spent case off and into the ejection chute opposite. There it is retained by a spring-loaded pawl until the bolt carrier again travels forward where a protruding lug pushes the spent case forward and out the ejection chute. It’s a very interesting system, the only flaw I found with it is that when unloading an unspent cartridge from the rifle, it does require a firm stroke of the charging handles to get the cartridge seated firmly in the ejection chute. This is not so much a flaw as much as it is a training practice needed to be followed. The ejection system is designed to be used on either side of the rifle, both the ejector and chute can be swapped from one side to the other in seconds.

The MDRX SE utilizes a standard side ejection system

Also new for 2020 is a new side ejecting MDRX, for those who prefer a simpler, more traditional ejection pattern. The side eject is available in. 223 Wylde only, and can also be swapped from right to left side ejection. There is also the added benefit of a lighter overall weight, and a less expensive price tag.

On the Range
With several barrels in hand, I took the MDRX into my mountain hide to test its function. I started out shooting with the sixteen-inch 308 Win barrel, and loaded with Fiocchi 150 Grain FMJ ammunition at one hundred yards. After zeroing the sights, I fired a few five-shot groups, which ended up being around two MOA in size.
I continued firing the rifle at several additional targets to see how it ran. I found the recoil to be much softer than the previous similar rifles I had shot, this surely had much to do with the Ratchet compensator. The trigger was very clean and crisp, the reset is quite audible, I attribute that to the highly conductive poly receiver who’s hollow construction makes a very resonant chamber. I fired several additional groups using additional ammunition types as well, American Eagle XM80 as well as some 168 Grain match ammo from both Hornady and Federal. The match grade ammo certainly provided better groups, they averaged right around one MOA.

The MDRX seen with 20 inch 6.5CM barrel and longer handguard

So with several hundred rounds through the rifle, and a respectable shooting and zeroed rifle, I figured it was time to test the metamorphosis of this multi-caliber gifted rifle. The barrel is removed from the MDRX using a five-millimeter hex wrench, the rifle comes with one, but I prefer to use the suggested eighty-inch-pound torque limiter. After removing the handguard via two loosened screws and one take-down pin, the barrel is released by loosening the two barrel clamp screws by about one turn, and then disengaging the barrel lock 180 degrees to allow the barrel to slide out the front of the chassis. The bolt must be locked open to the rear to complete this operation. I then installed the twenty-inch 6.5 Creedmoor barrel, seating it firmly towards the breach. The process is then reversed, turning the barrel lock 180 degrees, and then torquing the two barrel clamp screws to 80 inch-pounds with a torque limiter. Followed by re-installing the handguard, which I had swapped out for the longer one. The rifle had just transformed from a sixteen-inch 308 Winchester into a twenty-inch 6.5 Creedmoor, and I was excited to see the increased performance. The point of impact would not be the same from one barrel to the next, but it was on paper at one-hundred yards, so it only took some minor corrections.
The 6.5 Creedmoor shot very well, with 140 Grain ammunition from both Hornady and Desert Tech, the groups averaged much better, in the sub to half MOA realm. With this kind of accuracy, I couldn’t wait to take the MDRX out to more significant distances.

For several hours the rifle neatly piled up brass right in front of my shooting mat, the rifle never malfunctioned, and just kept eating magazine after magazine of ammunition. I also fired some S&B 140 grain ammo through the rifle without any problems, I would have liked to try some lighter loads like a 120 grain, but I didn’t get the chance.

A typical 5 shot group from the MDRX 223 Wylde 40 Grain Fiocchi (100 Yards)

The rifle is easily swapped to smaller caliber barrels as well, the 223 Wylde and 300 Blackout do require a little more though.
A change of the bolt, a magwell spacer, and a swap of the ejection chute are required in addition to the barrel change.
The 223 Wylde shot just as good as the 6.5 Creedmoor, sub MOA groups were easy when shooting good ammo.

The great performance of the MDRX was hard to deny, it is a very compact rifle, with incredible reach, and good accuracy. Desert Tech has upped the game with this rifle, and they stand behind all their rifles with a lifetime warranty. It would be a great rifle whether you are hiding in a tree stand, need a behind the seat truck gun, or anywhere you’d need heavy firepower in a compact package. Its larger calibers are certainly useful for big game hunting and some distant shooting, while the smaller calibers are great for quick target shooting in a 3-gun style competition or varmint hunting. The MDRX carries a higher than average price tag, but that is because it brings so much more to the table. The multicaliber option alone actually saves money by consolidating your training, and less money spent on optics and accessories. You literally could do almost every American shooting activity with this one rifle. Whether it is a home defense rifle or a suppressed ranch rifle, the MDRX is a do-all rifle if ever there was one.

-CBM

Short Action Black Magic

Am I the only one who was surprised by the rapid and exhaustive penetration of the 300 Blackout into the shooting world? I mean, I’d like to think that I had a grasp on what the hip kids shot. At first glance it didn’t even seem worthy of a second look. Sure, if your an AR guy and wanna spend a lot of time and money going movie quiet, then great, this slug’s for you. But what did it do for a guy with a serious precision rifle infatuation? Time would soon tell…
The guy that built my first custom rifle back around the turn of the century, was the first to mention it to me. He called it a Whisper, which is basically the same thing. I disregarded it as gun room talk, you know, two guys pretending to know a lot by saying things the other guy hopefully doesn’t know about?

Years later, as the blackout continued to gain market share, I found myself asking why people were building 300blk bolt guns. I had long since tailored my own sub sonic 308win loads, and to my simple mind, it didn’t make sense. A 30 caliber bullet going 1000FPS doesn’t care who pushed it there. And since the .308 had the added benefit of shooting bullets almost three times that velocity, it seemed silly to leave money on the table with the little blackout. Unless of course you were running an AR15 platform.

Fast forward to the era of my Desert Tech SRS, a rifle that most of you know dominates my trigger time. The compact and accurate SRS fit my needs like no other rifle can, and its ability to swap barrels has literally left thousands of gun collections collecting nothing but dust. I can run an abundance of calibers, both factory and custom, almost anything a guy can dream up from short action to long.

One of the last barriers in this overabundance of options for the SRS, was broken by Short Action Customs LLC a few years ago. Mark began a project that would eventually become a complete 223 conversion kit for the SRS. And before he could even sell the first one, the black plague was inquiring if he would also make a 300blk conversion kit as well.
Perhaps it was my skepticism of the blackout, that influenced his decision, or perhaps my mediocre street cred’s. But whatever the reason, Mark sent me a 300blk conversion kit to test out. A 16 inch 300blk barrel that would mate right up to the .223 bolt I already had, and a billet aluminum magazine with some slightly different cuts to it.
Testing loads
I am a sucker for load development, it’s like an attention deficit disorder. Regardless of what I’m doing, if there are empty cases on my bench, my mind wanders, considering what powder’s, what bullet’s, and the circumstances of their arranged marriage. I wasted no time getting deep into the black magic of loading this mysterious little cartridge.

Any writing about the 300blk would be incomplete without discussing its true purpose. As hinted by its name, the blackout is built around stealth. When loaded with heavy for caliber bullets, at sub sonic speeds, its sound signature is comparable to a pellet gun. The bullet is launched just below the speed of sound (a speed that varies depending on atmospheric characteristics) which in my neck of the dark woods is around 1000 fps. The slow speed of the bullet allows it to travel through the air without breaking the sound barrier, and the accompanying loud crack that some of us are familiar with. When a suppressor is added to the rifle, the report caused by rapidly escaping gasses, is also withdrawn. All that is left, is the sound of that gas escaping from the muzzle, resulting in a nearly unnoticed hiss.

In order to realize this secretive squall, quick burning pistol powders in small amounts are used. I had chosen the Hornady 195 BTHP, for many reasons but the most important one was that I was showing a large surplus in nothing else. After trying a few different loads, I found one that worked quite well. Using a mere 5 grains of Hi Skor 700X, the 195’s were hushing along just shy of the speed of sound. 700X may not be the ideal powder for the blackout I know, but when you have fifteen pounds of it, you have to find a way to make it useful. The small case of the blackout yielded more consistent velocities than .308win based sub sonic loads.

In no time at all, I found myself chuckling at the range. The incredibly quiet blackout was refreshing, and to my surprise it was pretty easy to get it to shoot well. I found myself calling cease fires, just so everybody could not hear the shot, followed by the distant metallic ping. Even my sub sonic loads had SD numbers in the low teens. With practically no load development, I was shooting near sub MOA 5 shot groups. And the supersonic loads (150gr Hornady BTSP’s) shot at almost 2000fps were even better (all accuracy testing was done at 100yds). The recoil, or lack of it was extremely satisfying, I could many times see my own bullets flying in the air on their way to the target. Like every other Short Action Customs, LLC barrel that I own, this one shoots with meticulous repetition. The accuracy, recoil, and cheap plinking fun that I have had with this little kit has certainly changed my perspective on the blackout.
100 yard 5 shot sub sonic groups, the top impact on both groups was 1st shot

With a covert ability to engage targets with the utmost concealment, this conversion kit would be perfectly suited for removing varmints from the barnyard. I suppose that LE and Military could use it for the same thing if they needed to quietly escalate something. At the same time, when loaded supersonic with lighter bullets, the blackout would also make a good short range plinking/hunting cartridge for game such as deer or hogs.

The 300blk conversion kit is a completely turn-key system, like any other conversion kit for the SRS. You simply drop the barrel in, torque it down, and swap either the bolt or bolt head depending on the configuration you have. The 10 round magazine fits right into the magwell like any other DT magazine. My kit came threaded for a suppressor, I assume they all will be unless ordered otherwise. But shooting this conversion kit un-suppressed would be silly in my opinion, as its entire enterprise is based on silence. I did experience a significant cold bore shift, whether this is a blackout thing, or a sub sonic thing, I dont know. But it is something to keep in mind for sure, when those hits have to count.
I used both a 308 suppressor, and a 338 suppressor on the little blackout, I didn’t notice any significant difference between them. But since the SRS is prone to multiple calibers, if I had to pick, I’d go with the 338. I wonder if a shorter barrel, would help lower SD numbers even further. A 10 inch blackout seems like it would be perfect, if it didn’t put my Covert on some NFA black list.

For those of you who are familiar with the 300blackout, you probably have experienced the same silly grin when you hear bullets thumping targets, as birds chirp nearby. For those of you who haven’t yet fallen under the spell, it shouldn’t take much.

I wont speculate as to when the complete blackout conversion kits will be available to order, but I believe the good people at Short Action Customs are working hard to get them ready. If you are interested a blackout conversion kit, shoot Mark an email at: mark@shortactioncustoms.com
(Dont call him and waste time because there are a lot of fine rifles being cranked out of that shop every day, and I dont need you slowing him down 😀 ) Visit http://shortactioncustoms.com/ for more information. photo credit: Ben Hetland
-CBM