Bushmaster's ACR Designated Marksman Rifle Part 1

Military, law enforcement and professional or personal security applications are all places the Bushmaster Adaptive Combat Rifle can be found in service. Modular in design, quick change barrel assemblies in lengths of 10.5″, 14.5″, 16″ and 18.5″ makes for flexible firepower. Assorted handguards, stocks and triggers allow for optimized configurations.

The current Bushmaster and Remington ACR are widely reported as beginning life is 2006 as the Magpul Masada; a highly configurable combat firearm featuring a multi caliber, quick change barrel system. Without the extensive resources necessary to make the Masada a production rifle, its design and manufacturing rights were licensed to Bushmaster in 2008.

Through efforts made by Bushmaster and Remington, both under common ownership within the Freedom Group, the “Masada” became the Adaptive Combat Rifle and both companies contributed to developing and refining its design. Bushmaster took the lead marketing to civilian and state and local law enforcement and Remington took the lead with military and federal law enforcement agencies.

Remington Defense versions has been developed in 5.56 NATO, 6.8 SPC and 300 AAC Blackout and in both semi auto and selective fire versions, but not mass produced. Bushmaster offers four ACR configurations at this time. All chambered in 5.56 NATO, models  differ primarily in barrel length, stock and handguards, with configurations tailored to specific application.

A designated Marksman is an assignment made within an infantry squad. The task of the assignee is to provide accurately placed, rapid fire on targets out to 500 meters. Rifles particularly suited for this type of mission are referenced as DMRs or Designated Marksman Rifles. The subject rifle is Bushmaster’s 2017 version of the ACR DMR. Of course, this is a representation as understood an old Air Force B-52 D Crew Chief where the Designated Marksman was a tail gunner and four .50 caliber machine guns.

Buttstock

There are multiple stock types for the Bushmaster ACR available. The ACR DMR is supplied with a Magpul PSR2 non-folding, significantly adjustable buttstock. An appropriate configurations for a designated marksman rifle intended to capitalize on longer range shooting opportunities. The PSR2 stock is rock steady.

A flash hider to facilitate suppressed fire

The Bushmaster ACR DMR is configured with an AAC Blackout flash suppressor. More specifically a 5.56mm 51T 1/2″-28 that also accepts 51T standard fast attach silencers. My SR-5 is a 90T fast attached silencer that travels with a finer tooth 90T version of the same flash hider, so it was a simple matter of swapping flash hiders appropriate for the silencer being attached.

In place, a compact and effective system of suppression that reduces sound pressure considerably, approximately 32 to 34 dB.

Ambidextrous Controls

Controls are in easy reach and intuitive in operation. I particularly like the bolt catch/release… sounds like fly fishing and charging handle. Contrary to what I’ve heard and read, there were no problems with the ambidextrous safety getting in the way on the right side.

The charging handle is mounted forward in the cantilevered receiver. The charging handle can be switched to the right hand side and it does not move when the ACR cycles.

Receivers, gas systems and handguards

The Bushmaster ACR’s receiver extends forward and supports the lower handguard assembly. The barrel floats. The top rail is part of, and runs the full length of, the receiver

The gas regulator selector as two positions, suppressed and unsuppressed, metering the gas volume to the gas piston and piston rod appropriately. The gas system is not direct impingement.

Disassembly

For folks with AR disassembly, this should look relatively familiar. Pull the magazine, check for empty, push Takedown Pin full right, rotate barrel and receiver assembly down, push Pivot Pin full right and lift off receiver. Grab the Action Spring and pull bolt carrier assembly rearward and out.

The Bushmaster ACR has a seven locking lug bolt as defined in the operating manual. What is often mistaken for an eighth locking lug is actually part of the extractor and is angle cut away from any potential locking surfaces.

The action spring and greater bolt carrier mass replace the AR 15’s slinky like recoil spring and buffer. The forward charging handle replaces the AR 15’s charging handle that slips over the bolt carrier with its operating handle at the rear of the AR 15 receiver.

Handguard removal is an easy deal. The captive handguard retaining pin is pushed all the way to the right and the handguard is slide forward and off, exposing the barrel retaining system.

Removing the handguard gives access to the barrel retention system. The locking lever is pulled down, rotated counterclockwise while compressing a plunger until motion is blocked and then the barrel is pulled forward and off.

Easy barrel removal makes it easy to clean and perform maintenance and it makes barrel swaps a simple proposition. Use of an interrupted thread barrel nut speeds removal and it is a strong retention design. The gas system travels with the barrel and is as easy to disassemble to clean.

ACR versus AR discourse…

I find myself spending a good deal more time looking at new firearms and reading about them in credible publications and then discussing them with personal or industry friends and associates. Gun forums mostly make me sick. For the most part, technical expertise is absent, opinions are expressed in vial terms, and discussions are quickly reduced to lobbing personal insults. I would suggest that theme is exceptionally true concerning this subject. AR owners apparently believe video gamers buy ACRs and ACR owners tend to think AR owners are newly degreed or in process degreed engineers with red neck tendencies. Hey, don’t shoot the messenger.

My method of assessment is quite controversial…

Disassemble and reassemble. If I can do it myself, the task is easy. If I can get someone I know to assist and get it done, the task is reasonable. If I have to ship the gun back to the manufacturer in pieces, it is too complicated. Never sent one back in pieces, but hope is alive. Bushmaster ACR disassembly is easy and I really appreciate the absence of one of twenty six thousand handguard attachment schemes.

Check for blood trails and count Band-Aids. If there is no clean up and my wife has applied no Mickey Mouse Band-Aids to my person, fit and finish of parts is exceptional. One Band-Aid is still pretty good. Pale, severe blood loss and passing out; not so good. No Band-Aids, the Bushmaster ACR fit and finish in non-injurious. Yes, rails are like cheese graters for the inexperienced as are all MIL-STD 1913 Picatinny rails. Rail covers can protect the uninitiated and Bushmaster might put them in the box.

Controls, placement and intuitive function. If I can get the bolt closed without referencing the manual, if I reach a digit for a safety and can find one, if I can open the action without removing a scope, if the trigger has less than nine pounds of pull, I am pretty much a happy camper. If I need to reference the manual multiple times to insert a magazine or if an oxyacetylene torch is required for routine maintenance; big problem. The Bushmaster ACR’s controls are easy to operate, positive in actuation and intuitive in placement. No sneaking under low hung scopes to fish for the charging handle and the bolt catch/release is where it should be.

Adaptability. Changing stocks, handguards and barrels without tools and without having to change many associated pieces is the best. Changing accessory pieces as assemblies and with common hand tools is still good. Changes requiring special tools, torque wrenches, Loctite, etc, is not good. In this regard, the Bushmaster ACR is the best. The flip side of this feature is at the center of the AR-ACR debate.

ARs are often box of parts firearms with owners often more interested in keeping up with the newest trends in parts and assemblies and constructing personalized firearms than  putting finished firearms to work. The result is that some that are terrific in looks, accuracy and reliability and others are unreliable, possess a quarter inch of excessive headspace and produce buckshot accuracy.

The Bushmaster ACR is not a tinkerer’s firearm, it is a complete and solid integration of systems offered in enough configurations to cover most mission objectives. Owners can purchase three different types of buttstock, two handguards and four barrel lengths, all offered by Bushmaster. Within that spectrum, an ACR can be placed into service for self defense, hunting or competitive or recreational range work. For aftermarket pieces, Geissele, the OEM trigger supplier, also offers some alternative types. That said, there is not a thick aftermarket parts catalogue to pick and choose from.

Gas system. I prefer the gas pistol/piston rod arrangement over direct impingement systems. In my experience they are easier to tune to ammunition and they are cleaner running. Something about not having highly pressurized bore barf being pumped into the receiver just works for me.

What’s next and what’s missing?

After all is said and done, a rifle slated for a designated marksman, should be accurate and shoot with repeatable precision. And that is where we are off to next, live fire and paper punching to better assess reliability of function and performance.