Adaptive Combat Rifle The Adaptive Combat Rifle ( ACR ) is the production name for an updated version of the Masada Adaptive Combat Weapon System . It is an assault rifle platform designed by Magpul Industries of Erie , Colorado . In late January 2008 , Bushmaster entered into a licensing agreement with Magpul whereby Bushmaster would take over production , future development , and sales of the Masada . Remington Arms are currently contracted to manufacture the rifle for the US Military and US Law Enforcement agencies . The rifle was initially developed over a period of five months and was planned to replace the M16 completely independent of government funding . Prototypes were displayed at the 2007 SHOT Show in Orlando , Florida . Originally scheduled for release in the second quarter of 2008 , Bushmaster announced on May 16 , 2008 , that the consumer release would be delayed until Q1 2009 , owing to a focus on military projects . On November 18 , 2008 , Bushmaster released a statement saying , " The ACR is being redesigned to be a superior offering to compete for the next generation US Army infantry carbine and subcompact weapon requirement and will be available to select customers in 2009 . " The ACR was one of the weapons displayed to U . S . Army officials during an invitation - only Industry Day on November 13 , 2008 . The goal of the Industry Day was to review current carbine technology prior to writing formal requirements for a future replacement for the M4 Carbine . The ACR was part of the Individual Carbine competition to replace the M4 . History . The original Magpul Masada design represented a combination of several recent rifle designs , incorporating what was considered by its designers to be the best features of each in a single , lightweight , modular rifle platform . Design features from the Armalite AR - 18 ( short - stroke gas system ) , the FN SCAR ( upper receiver , charging handle location ) , the Heckler & Koch G36 / XM8 ( liberal use of polymer components ) , and the M16 / AR - 15 ( trigger pack , barrel , fire control group ) were present . The rifle also included several features developed by Magpul , such as a quick - change barrel / trunnion system , adjustable gas regulator , non - reciprocating charging handle , and storage compartments located in the stock and grip . Just prior to the deal with Bushmaster , Magpul made additional changes to their design — the most obvious of these was the relocation of the ambidextrous operating handle to a forward position ( somewhat similar to the Heckler & Koch G3 and Heckler & Koch MP5 series of weapons ) . Experts from Magpul Industries had on several occasions mentioned that depending on the barrel length of the weapon , the rate of fire was estimated to be in the range of 600 – 800 rpm ( this is an estimate ; specifics have not yet been verified ) . The weapon ' s caliber could easily be changed by replacing the bolt head , magazine , and barrel . In January 2008 , the design of the Magpul Masada was licensed to Bushmaster Firearms International and the production version of the Masada became known as the Bushmaster ACR . Availability and recall . The ACR was stated to be available in the 2nd Quarter of 2010 for military , government , and commercial customers . It was available in greater quantity ( tens of thousands ) in the commercial marketplace in 2010 . According to an official press release from Bushmaster , the rifle had a suggested retail price between $ 2 , 685 – $ 3 , 061 . 00 – twice as much as early price quotes of " around $ 1500 , " causing public outcry and dismay of the rifle from a large portion of the firearms fraternity and potential civilian end - users . Semi - automatic versions are available to the commercial market from Bushmaster , and selective fire versions are available for military and law enforcement under the Remington name . As of April 2010 , civilian market rifles were available for sale . On October 15 , 2010 , Bushmaster issued a recall of all ACR rifles instructing users to " Please immediately discontinue the use of your ACR rifle " along with instructions to contact customer support for an RMA . Bushmaster stated that the recall was issued due to " a possible firearms performance issue that may develop with a small number of ACR rifles " and goes on to state that " Bushmaster discovered a design flaw which could result in multiple rounds firing continuously when the trigger is pulled " . Bushmaster has stated that it will cover all of the costs associated with the repairs to the recalled rifles . Design . Bushmaster Firearms , with the help of Remington Arms , ( a sister company in the Freedom Group , Inc portfolio that includes Bushmaster , Remington , Marlin , and DPMS Panther Arms brands ) made extensive design changes based on intensive environmental and functional testing specifically to meet the emerging requirements of the US military in both the carbine and subcompact weapon versions of the ACR family . It was made to endure certain conditions such as exposure to sand , dirt , mud , and water . The ACR is currently offered to military and civilian personnel in . 223 Rem / 5 . 56mm NATO . Bushmaster and Remington have planned kits to switch the caliber of the rifle to 6 . 8mm Remington SPC just by replacing the barrel , bolt carrier , and magazine , however to date none have been produced . The ACR has barrel length options of 10 . 5 ″ , 14 . 5 ″ , 16 . 5 " , and 18 ″ . Commercial models have barrels only in 16 . 5 " . Barrels are hammer - forged and hardened with a nitriting process rather than having chrome plated bores as some other rifles . Among options for the ACR are various stocks including a fixed adjustable ( in terms of length of pull and cheek weld ) , folding adjustable ( folding and six - position telescoping ) , and sniper stock based on the Magpul PRS stock . The Bushmaster model ' s handguard is polymer with heat guards and attachable aluminum trirails , while the Remington model has a five sided aluminum handguard that can be user configured with MIL - STD - 1913 rail elements . The magazine conceived for the 5 . 56mm version of the ACR rifle is called the Magpul PMag , a high - impact , 30 - round polymer magazine claimed by Magpul to be significantly more resistant to wear , shock , and harsh environments than other counterparts on the market . The PMag is STANAG 4179 - compatible , as it will readily fit any STANAG magazine firearm , including the M16 rifle family . The initial ACR design was offered in the Army ' s Individual Carbine competition . In late 2011 , Remington unveiled an improved version specifically for the competition . Improvements included a magnesium lower receiver , A2 - style pistol grip , collapsible but non - foldable stock , carbine length gas system , a new barrel nut ( which eliminates the quick change barrel ) , and a folding charging handle . These changes made the weapon 1 . 8 lbs lighter . The Individual Carbine competition was cancelled before a winning weapon was chosen . Remington also unveiled a sub - compact version called the ACR - C Personal Defense Weapon ( PDW ) . This version retains the features of the Individual Carbine variant , except that the folding stock was kept and the barrel was shortened to 9 . 5 in . With the stock folded , it is only 19 . 5 inches long . Miscellaneous . The rifle was originally named after the Siege of Masada . Magpul company literature about the rifle states that , " Magpul Industries is not Jewish owned or Israeli backed , however Magpul has always found the story of the Masada as a bold example of defiance . " When production rights were signed with Bushmaster , the Masada name was dropped from the product .