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.

Gun World - - Contents - By Richard Schutz

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.

SIGHTS/OP­TICS

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.

AM­MU­NI­TION

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.

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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 is ad­justable for length of pull and cheek­piece height.

It also has a rear, 1.5-inch web sling at­tach­ment point and

a sin­gle-point sling an­chor point. It does not col­lapse or swing

to the side.

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 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 her­itage shows in the in­te­gral pis­tol grip. It fea­tures a com­part­ment for a re­mov­able CR123

(two) bat­tery holder.

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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 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.

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