The Remington ACR was one of the weapons displayed to U.S. Army officials during an invitation-only Industry Day on November 13, 2008.

[8] Design features from the Armalite AR-18 (short-stroke gas system), the FN SCAR (upper receiver, charging handle location), the Heckler & Koch G36 and XM8 (wide use of polymer components), and the M16/AR-15 (trigger pack, barrel, fire control group) were present.

[10] 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.

[11] 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 MP5 series of weapons).

[13] The rifle was initially developed over a period of five months and was planned to replace the M16 completely independent of government funding.

[14] 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".

[15] 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) have also made extensive design changes based on extensive 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.

They made sure that the ACR will be capable to endure certain conditions such as exposure to sand, dirt, mud, and water.

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.

[18] Remington also unveiled a sub-compact variant 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 inches.

It includes the Magpul PRS adjustable stock, a longer 18.5 in (470 mm) full profile 416 stainless steel melonite coated barrel (that retains the carbine-length gas system) with 1:7 inch rifling twist, and a Geissele enhanced trigger.

The revelation caused public outcry and dismay of the rifle from a large portion of the firearms community and potential civilian end-users.

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".

[29] The Bushmaster ACR was known to be used in 2012 by Polish soldiers under the Służba Wywiadu Wojskowego (Military Intelligence Service).

[32] The key idea of the ACR's modular system, is that it will provide a wide variety of configurations within a matter of minutes.

[32] A three position (safe, semi-auto and full auto) fire selector lever is located over the pistol grip.