BUSHMASTER ACR DMR
The ACR DMR brings a new level of precision and adaptability to the ACR lineup that will give the AR a run for the money.
The first Bushmaster adaptive combat rifle (ACR) became commercially available in 2010. It was based on a Magpul design called the Masada, which was introduced in 2007. The draw of this rifle was its ergonomics and modularity. The ACR was initially offered only in Basic and Enhanced models. In 2014, Bushmaster announced a significant addition to the ACR line: the ACR DMR (Designated Marksman Rifle). Unfortunately, due to the relocation of production operations from Ilion, New York, to Huntsville, Alabama, the rifle was not available for sale until November 2016.
Reintroduced at the 2017 SHOT Show, the ACR DMR brings a new level of precision and adaptability to the ACR line. In addition to those features found on the Basic and Enhanced ACR models, the DMR version adds a fixed Magpul PRS-2 buttstock, a quick-change, 18.5-inch barrel and an aluminum handguard with 1913 MIL-SPEC rails on three sides.
OPERATION AND SPECIFICATIONS
The Bushmaster ACR DMR utilizes a regulated short-stroke, gasoperated piston system to operate the bolt carrier group (BCG). This system keeps hot gases and fouling material from entering the receiver and BCG. The gas regulator allows the operator to set the system for either suppressed (“S”) or unsuppressed (“U”) operation with a simple twist of the selector.
The upper receiver is made from extruded aluminum, and the lower receiver is molded from a proprietary composite polymer. There is no dust cover or forward assist as are found on most traditional AR-15 platforms. I didn’t miss them either. The forward operating lever can be used to assist the forward movement of the BCG. The upper and lower receivers are opened by removing a single pin in the same manner as an AR-15. The hinge pin can be removed to fully separate the upper and lower halves.
REINTRODUCED AT THE 2017 SHOT SHOW, THE ACR DMR BRINGS A NEW LEVEL OF PRECISION AND ADAPTABILITY TO
THE ACR LINE.
A non-reciprocating, forward-mounted charging handle is used to manually operate the BCG. This handle can be installed on either side of the rifle’s upper receiver to accommodate either right- or left-handed shooters. A full-length, monolithic 1913 MIL-SPEC rail is machined into the top of the upper receiver, which runs from the front of the stock all the way to the front of the handguard.
A three-sided aluminum handguard has 1913 MIL-SPEC rails machined into all three sides and is easily removable with the removal of a single captive pin. It can be replaced with a Bushmaster polymer unit if desired. There are no less than five Q.D. sling mounts, a sling loop on the left rear of the buttstock and a single-point attachment point on the left side, forward on the buttstock.
The BCG can be removed by simply sliding it to the rear once the upper and lower receivers have been pivoted to the open position. Once out of the upper receiver, the BCG can be stripped for cleaning in five easy steps. This is somewhat of a moot point, however, because the BCG stays much cleaner than that of a direct-impingement (D.I.)-operated AR-15. You’ll find no caked-on carbon or gas sealing rings on the ACR DMR’s bolt.
It is not necessary to remove the barrel for cleaning. However, if you want to do so, or if you want to install a different barrel, it requires only five easy steps: After locking the BCG to the rear and removing the handguard, simply lower the barrel locking lever, rotate it approximately one-quarter turn counterclockwise until it stops, and then pull the barrel assembly forward out of the trunnion. It couldn’t be any easier (unless someone does this for you). Bushmaster claims that the zero of the barrel will not be lost by removing and reinstalling it.
Removing the gas piston for cleaning is easily accomplished in only three steps and can be done with the barrel attached or removed from the upper receiver.
The composite polymer lower receiver has a fixed Magpulstyle pistol grip with a slide-out compartment designed to store two CR123 batteries. A Geissele two-stage trigger provides a smooth-as-silk trigger pull, which breaks cleanly at an average of 4 pounds, 5.6 ounces, for 10 consecutive pulls (as measured by a Lyman digital trigger pull gauge).
To accommodate both left- and right-handed shooters, the magazine release, bolt lock and safety selector are all ambidextrous. The magazine release operates with a pushbutton on either side of the receiver. The bolt release is different from an AR-15 in that it is located low, in front of the trigger guard. Pushing it up locks the bolt back; pushing it down releases the bolt. This can easily be operated using one’s trigger finger. The selector switch (safety) is located
at the same position as on an AR-15 and works in the same manner. I found the lever on the left side a bit too short to operate cleanly with my thumb.
The ACR DMR comes with the Magpul PRS-2, which is an excellent buttstock. It’s adjustable for length of pull and has an adjustable cheekpiece. I’m not sure why anyone would want to, but swapping out the Magpul PRS-2 buttstock on the ACR DMR is a piece of cake: Simply push out the rear takedown pin, pivot the upper receiver from the lower receiver, push out the stock retaining pin just below the takedown pin and then
A GEISSELE TWO-STAGE TRIGGER PROVIDES A SMOOTH-AS-SILK TRIGGER PULL, WHICH BREAKS CLEANLY AT AN AVERAGE OF 4 POUNDS, 5.6 OUNCES …
slide the buttstock upward and out of the lower receiver. One of the other available Bushmaster ACR buttstocks can then be slid into place and pinned into position.
MODELS AND ACCESSORIES
The ACR DMR’s siblings include the ACR Basic, ACR Enhanced and ACR SBR (short-barreled rifle) models, available in black and coyote. Currently, all ACR models come chambered in 5.56x45 NATO (.223 Rem.) only. However, caliber conversion kits have been talked about in the past, and the website and manual still have references to multi-caliber kits being available (although these are not actually available in the store). The word from Bushmaster is that the caliber conversion kits will be a priority for 2017.
Bushmaster offers two optional buttstocks, one optional handguard and three optional hammer-forged barrels. Many traditional AR-15 accessories will also fit on the ACR DMR. Unlike the AR-15, the ACR has an integral pistol grip that cannot be swapped out. The grip worked well for me, but some shooters might think otherwise.
Based on the intended use of the ACR DMR for longer-range situations, I mounted a Nightforce ATACR 7-35x56 F1 riflescope using a Nightforce 34mm Ultralite Unimount. This is a little more scope than is necessary for this rifle (but, as with money and fast cars, you can’t have too much of a good thing!).
For long-distance shooting, the Nightforce scope with the .250 MOA MOAR reticle is an excellent match for the ACR DMR. Unfortunately, it costs more than the rifle. With the availability of excellent scopes these days, it’s not unusual to spend more on glass than on iron when setting up a new rifle-and-scope combination.
The ACR DMR is chambered for the 5.56mm NATO round. Therefore, .223 Rem. ammunition can also be used. Various brands of ammunition and bullet weights were used during the evaluation of the ACR DMR. With the 1:7-inch-twist rifling, I expected that some loads using heavier bullets above the “standard” of 55 grains might work well. That proved to be true, because the top three loads for accuracy used 62- to 69-grain bullets.
For velocity and accuracy evaluations, I used various commercial 5.56 NATO and .223 Rem. ammunition with bullet weights from 53 to 77 grains.
FROM THE SHOOTING BENCH
At the first range session, I sighted-in the ACR DMR at 100 yards using PMC 55-grain FMJ ammunition. I then broke in the barrel with another 40 rounds of various brands and types of ammunition.
I then began shooting various factory loads for accuracy and velocity. I fired three five-shot groups with each factory load and cleaned the barrel bore after each load, followed by two fouling rounds. Five factory loads were fired for this session. The ACR DMR was a dream to shoot, and the Geissele trigger was smooth and crisp, as always.
During two more range sessions, I evaluated accuracy and velocity for several more factory loads. The same protocol was used as during the initial range session, and the rifle, magazine, ammunition continued to perform flawlessly throughout.
The Remington 69-grain Sierra MatchKing BTHP load turned in the best average for three five-shot groups: 1.17 inches. Hornady Black 62-grain FMJ was a close second at 1.34 inches. Federal Premium 69-grain Sierra MatchKing BTHP load came in third at 1.79 inches. The smallest individual group was from the Hornady Black 62-grain FMJ at .91 inch. The top two loads produced approximately 1.25-inch averages for three five-shot groups—quite acceptable for a rifle of this type. All seven loads were less than 2 inches for three five-shot groups.
YOU CAN HAVE BOTH!
The modularity and ambidextrous operation of the ACR DMR are what really set it apart from most AR-15 style rifles. The
THE ABILITY TO CHANGE THE BARREL IN LESS THAN TWO MINUTES WITHOUT TOOLS AND WITH A SOLID LOCKUP IS PROBABLY THIS RIFLE’S BIGGEST ASSET.
The ACR DMR receiver breaks open just as on a traditional AR-15. The Geissele two-stage Super ACR trigger is different than a traditional AR-15 trigger in that there are no pins that go through the polymer lower receiver. The ACR DMR’s Magpul...
The ACR DMR features a left-side magazine release button, Q.D. sling attachment point, single-point sling attachment anchor point and an integral pistol grip.
The upper receiver extends from the front of the buttstock to the front of the handguard. This provides a monolithic upper with a 1913 MIL-SPEC top rail and a place for the replaceable handguard to lock into in the front. The Magpul PRS-2 buttstock...
The author fires the ACR DMR from the bench for velocity and accuracy evaluation. Velocity was calculated at the muzzle using a LabRadar device.
The gas piston/ regulator assembly is easily disassembled for cleaning.
The bolt carrier group slides into the upper receiver. Note the recoil rod, spring and nylon buffer.