Desert Tech MDR

By Dean Roxby

The long awaited Desert Tech Micro Dynamic Rifle (MDR) is very close to being released for sale to the general public.

The MDR was first announced at a press conference at SHOT 2014 (January 2014). At the time, Desert Tech (DT) was planning on a release date of mid-2015. However, this turned out to be somewhat optimistic. Each year following, DT had a booth at SHOT and showed off prototype guns with minor changes and upgrades made.

Ever since attending that first press conference, this author has been intrigued by the clever design. I wrote about it for SAR/SAW in early 2014 (https://www.smallarmsreview.com/display.article.cfm?idarticles=2657).

As I have been following this rifle since the original 2014 press conference, this allows me to discuss the evolution of this most intriguing rifle. I will first describe the general layout and operation of it and then take a closer look at some of the changes made during its development.

To briefly review, the MDR is a modular bullpup design, with a short stroke gas system.

It has the ability to change calibers by simply swapping the barrel, bolt head and a magazine insert. It was also designed right from the beginning as a truly ambidextrous firearm. In addition to the standard 16-inch (406 mm) length MDR, there is also the MDR-C version. The C, or Compact, version is amazingly short, having a barrel only 10.5 inches (267 mm) long. Of course, due to the bullpup layout, even the standard full-size barrel version is a very compact 27.1 inches (688 mm) overall.

The MDR-C uses a shortened forearm handgrip also, in addition to the above-mentioned short barrel. This turns an already compact rifle into a surprisingly short carbine or Personal Defense Weapon. And yet it still fires potent 5.56 NATO or 7.62 NATO rounds, not low-powered pistol rounds. The standard MDR rifle can be re-configured to become a MDR-C by replacing the barrel and handguard with the short versions.

Back in 2014, DT stated that they planned to produce caliber conversion kits in five calibers. These were: 5.56x45 NATO, 7.62x51 NATO, 300 Blackout, 6.8 mm Remington SPC and 7.62x39 Russian. Currently, the first two chamberings will be 5.56 and 7.62 NATO, with the 300 Blackout available as a conversion kit only. They have not given up on the 6.8 mm or 7.62x39 rounds, but they will come later. Regarding the 5.56 caliber, there is an ongoing concern about whether it is safe to interchange the original .223 Remington version with the later 5.56x45 NATO version. DT solves this issue by cutting their chamber to .223 Wylde dimensions. The Wylde chamber is designed to accept both the .223 Rem and 5.56 NATO safely.

Changing barrels and calibers within the same family of cartridges is simple enough, but how do you change to a completely different class of cartridge? In this case, how can this rifle handle both 5.56x45 and 7.62x51 rounds? They take different size magazines, with the 7.62x51 mag being noticeably larger. That is where a magazine insert is used. If you are set up for the larger 7.62 round, the insert is removed, and the magwell can accept the larger AR-10 SR-25/DPMS-type magazine. If the rifle is to be set up for 5.56, the insert is locked in place, and standard AR-15 mags can be used. Very clever!

As noted above, the DT design team wanted the MDR to be completely ambidextrous in operation. All the controls are accessible from either side, and the empty brass cases are dealt with in a clever fashion. There are now two non-reciprocating charging handles, one on either side of the receiver, that look somewhat similar to an FN-FAL charging handle. The first prototype rifles displayed in 2014 only had one changing handle then. The rotating safety selector is located directly above the pistol grip and is accessible from both sides by your thumb. The safety has been redesigned with a shorter throw than previous versions.

The main magazine release is just forward and above the pistol grip. Again, there are two buttons, one on each side of the gun, and they are depressed by your index finger. A second mag release lever is located on centerline, just forward of the magwell. This allows you to drop an empty mag by depressing either button with your trigger finger or by squeezing the lever as you grasp the magazine with your opposite hand.

The gun has a Hold Open Device activated by the floorplate of an empty magazine. After dropping the empty mag and inserting a full one, the bolt can be closed by pressing on a button located on the centerline, just behind the magwell, similar to the Israeli Tavor.

One of the cleverest aspects of the MDR is the way it ejects fired cases. With many bullpups, the gun is exclusively right-hand ejection. As long as you are firing from the right shoulder, this is fine. However, if you fire from the left shoulder, you risk getting a mouthful of hot brass. The MDR handles this issue by directing the spent cases forward. Upon firing, the case is extracted rearwards as usual. Then, instead of being forcefully flicked directly sideways to the right as the bolt comes rearwards, it is gently moved to the right and held in place. Then the bolt and bolt carrier return forward to pick up another live round. As this happens, the edge of the bolt knocks the empty case forward and out. A stamped steel cover plate with a trough in it guides the case out. This trough-shaped cover plate has been revised somewhat. The original cover plate was open at the end. This could possibly let debris in, so a small spring-loaded flap was later added. As well, the cover plate can now be moved to the left side of the receiver to allow for a true left-hand ejection. No special tools are required to do this swap other than an empty cartridge case. It is interesting to note that the last fired case is not ejected as the bolt HOD holds the bolt rearward. Then after the empty magazine is exchanged for a fresh one, the bolt release just behind the magwell is activated, and the previously fired case is ejected forward. This can be seen in the YouTube video mentioned below. If you wish, the cover can be opened for traditional right-hand ejection. Opening the cover also allows for a visual safety check of the chamber.

Another change made is a short Picatinny rail segment built into the barrel gas block. This Pic rail lines up with the full-length rail on the receiver and forearm hand guard. If desired, this short segment of Pic rail can have a small reflex sight mounted permanently. This allows for the sight to remain zeroed to the barrel when doing barrel changes.

If a suppressor is desired, a special enlarged handguard is available that clears the recommended AmTac CQBM suppressor. The gas system has four positions: Normal, Fouled, Suppressed and Closed.

During SHOT 2017, DT invited media and other guests to test fire the MDR at a range in Las Vegas. Due to the huge interest, we were limited to 6 rounds each, on a very short indoor range. So no serious testing was possible, but enough to wet my appetite for more!

The MDR rifle will be shipped in a custom-fitted, hard plastic case. As the barrel is easily removed, the case is dimensioned for the gun with the barrel removed, allowing for a smaller package. The MSRP is $2275 for the 5.56x45 mm version, and $2525 for the 7.62x51mm version. Both chamberings are available in either black or FDE for the same prices. A YouTube video from DT shows this exciting rifle in action: https://www.youtube.com/watch?v=MDn_Gp2QWss&feature=em-subs_digest.

This article first appeared in Small Arms Review V21N4 (May 2017)
and was posted online on March 17, 2017


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