Tag Archives: 762

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.

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.
But if you are a stamp collector like many of us are, you can also get the SBR conversion kit for the MDRX. The 11.5 inch barreled Micron conversion kit makes any MDRX into one of the shortest and compact rifles available. All these conversion kits make the MDRX an extremely adaptable rifle, to whatever mission specific purpose you need.

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.

Various MDRX accessories make it an extremely versatile platform

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.


The Desert Tech MDR in 5.56

There has been lots of excitement surrounding the Desert Tech MDR lately. With some rifles shipping since late last year, and many more about to drop, the hype has reached its peak. The Micro Dynamic Rifle  brings Desert Tech’s multi caliber capability to a an auto loading rifle. All of the rifles that have been delivered to customer so far have been 7.62 rifles, but I got a lucky chance to get an up close look at some of the first 5.56 rifles. After a few hours of shooting it, I decided to write a little more about it.

The MDR is a bullpup rifle, and currently there are 7.62 and 5.56 conversions available for it. I have spent extensive time with the 7.62 versions of the rifle, and have found it to be a very fun rifle. The function of the rifle is very intuitive, the controls may take a moment to get used to but are otherwise very friendly. In my experience, the controls wear in with use, and only get better. The initial feel is that the mag release is stiff, and the trigger can be a bit scratchy. But with some range time, both of those issues go away, and the trigger is quite nice. I dont even think about the mag release anymore, it is smooth and easy to operate.

The MDR has big shoes to fill. As many of you are aware, Desert Tech makes some of the best precision rifles available today. And having sired the MDR, Desert Tech is expected to bring the same quality and presentation its other rifles are famous for. Quality triggers, better accuracy than the competition, all in a multi-caliber rifle shorter than its peers.

Having had plenty of trigger time with the 7.62 version of the MDR, I was very excited to try out the smaller conversion in 223/556. I was actually lucky enough to assemble the rifle from scratch. Or at least, from a small pile of parts. Click here to see assembly.

After some humbling experiences, I was happy to see the gun work like it had been built by the pros. It took very minimal tuning to get the rifle running just like a swiss watch. It was time to take it out into the wild, and get it hot.


Coldboremiracle Junior feeling out the MDR

The 5.56 MDR was a dream to shoot, comparing it to the 7.62 version of the rifle, which has significantly more bark. Recoil was negligible, a smooth and solid impulse. The ejections system pumped the hot brass out forward and to my right, making nice little piles. The rifle manages almost like a pistol, it is very easy to keep on target even during sustained firing. I used the gas block mounted Desert Tech Reflex Optic for much of the shooting. But it didn’t take long for the marksman in me to come out, so I switched over to a Kahles 312i for some accuracy testing. After all, only accurate guns are interesting, at least to me.

I also couldn’t pass up the opportunity to try out my new Yankee Hill Machine Turbo 556 suppressor. The MDR was a perfect host for it, and its uncivilized to shoot unsuppressed. You can read more about the Turbo here.

I was shooting some 55 grain ball ammo for the majority of the trip. This same ammo usually prints groups in the one inch category with my other custom 223 rifles, and in the MDR it was about the same. Five shots was probably just under an inch at 100 yards. I also wanted to try one of my pet AR loads for long range, which included a Hornady 75 grain BTHP and some RL-15.

After getting the rifle sighted in, I was quite impressed with the MDR’s accuracy. This was the first group I shot after zeroing the rifle, its only three shots but clearly shows the rifle’s potential.  The MDR clearly likes this load with the Hornady’s, so I may have to revisit with more ammo , and more range.

The rifle functioned great through the three or four hundred rounds that I put through it. There were only a couple issues that I quickly resolved, a spring that is part of the ejection system had not been installed properly. I cant blame anyone but myself there, and after I corrected the problem it was flawless.

I tried out several different magazines in the rifle. First I had to try the classic GI metal magazines that surely litter ever gun room across the country. The mags fit perfectly, fed like a million bucks, and even dropped clear with no need for assistance. I also had a couple Brownells Gi clone magazines. I bought them a few years ago on sale, as far as I can tell they did a great job cloning the old magazines but with new coatings and Brownells quality. In addition to those two types, I also tried out some standard Magpul Pmags, in both 20 round, and 30 round configurations. I am happy to report that all of them worked great, no feeding issues at all. That should come as good news to all those prospective MDR owners who already have a broad magazine inventory.

Another big concern to those interested in the MDR is the adjustable gas system. The rifle I build had a three position gas selector, though I understand that a selector with more settings (five or six) will soon be available for all MDR rifles. That said, this rifle worked great with the standard three position gas selector. I ran it on adverse for the first hundred or so rounds, to help break it in. I then changed it over to normal, and then to the suppressed setting when I attached the suppressor. I can see where a gas valve with more choices would be helpful, as even on the suppressed setting there was enough gas exiting the receiver that I could smell it. But honestly it wasn’t a big deal to me, I kept shooting along without any concern. If you shoot in an enclosed or indoor range, I could see it maybe becoming an issue. But easily resolved with a lower gas setting.

I also decided to see how the gun would run without the ejection chute installed, I have seen and been asked many times how it works. For me it isn’t a big issue, since in my experience most ejection issues/jams in the MDR are not related to the chute. But I can understand why some would want to know, so I gave it a try. With the chute removed, the gun ejected brass directly out and to the rear, about to my four or five o’clock. It occasionally would throw one to the three o’clock, but it didn’t seem to care, as it continued to chew through the rounds. Speaking of chewing, the 556 conversion on the MDR seems to be fairly mild on the brass. I assume it is because of the larger extractor to rim ratio, as well a smaller gas volume and recoil impulse.

My overall impression with the 556 MDR was one of pure enjoyment. Perhaps Im just used to shooting the 762 version, and other heavier recoiling rifles, but I just couldn’t stop pulling the trigger on this gun. The accuracy makes this rifle at the top of my wish list, and I intend on getting some more time behind it soon. Perhaps a coyote hunt or some other adventure. I will be getting one as soon as conditions permit, and probably a 6.5Creedmoor barrel to go with it for more serious work such as distance.

For those of you waiting for the 556 MDR, hang in there if you can, it is worth it.


Oh Wait! there’s a Video too: