The Colt M5 Carbine, not SIG Sauer’s XM5

The Colt M5 is one of Colt Defense’s first new products since they were purchased by CZ in 2021 to form Colt CZ group. A little history on the AR-15/M16/M4: Colt’s manufacturing inc purchased the AR-15 design from Armalite in 1959, they had been producing military versions (such as the M16 and M4) for the US Department of Defense until they went bankrupt in 2013. Colt’s manufacturing inc restructured into Colt Defense in 2016.

During their long history with the AR-15, Colt’s Manufacturing inc and Colt Defense (USA) has done little to improve the design before going bankrupt, most innovations came from Canadian Diemaco (purchased by Colt Defense and renamed Colt Canada in 2005). Public innovators included US Department of Defense ran Picatinny Arsenal and Naval Surface Warfare Division Crane Indiana, Knight’s Armament Company is the best known private innovator.

With Colt Defense’s 2021 acquisition by CZ, we are seeing increased innovation of legacy products. This innovation is probably too late to win a US DOD contract, but we have yet to see.

Lower receiver control upgrades from previous Colt M4s and AR-15s


Ambidextrous selector levers come stock, they turn in 90 degree increments. The selector of the display model will still not switch to safe after the hammer is dropped (per DODs original M16 requirements) According to a Colt/CZ representative, the selectors can be special ordered to switch to safe on a dropped hammer with closed bolt.

Magazine catch and release, Bolt catch and release

A second magazine release button is added to left side, adapted to the 5,56 lower receiver from the CM-901 modular multi calibre receiver.

A second bolt catch and release control is added to the right side, it was also borrowed from the original CM-901 design but with slight modification. The generation 2 CZ Colt group AR pattern right hand bolt release can now lock back the bolt with the pointer finger when the changing handle is pulled back. In other words: the bolt can be locked open to clear and make the weapon safe at anytime, without taking the right hand off the pistol grip. This ambidextrous bolt catch and release does not infringe on patent US8359966B1 for the “Ambidextrous rifle bolt stop release” (known commercially as the PDQ) owned by Teal Blue Bravo LLC.

Upper receiver upgrades from previous Colt M4s and AR-15s


The handguard is a new type of design for Colt, it is a nearly a true free float (minus the gas block) but it is not monolithic to the upper receiver.

The monolithic upper/handguard design incorporates both into one piece. This design had been used by Colt Canada for years, notably in the British SAS L119A2. The monolithic upper presented both licensing and design problems. Lewis Machine and Tool (owned by KRL holding company inc) has the right to patent US8234808B2 until August 2026. Until then, they are entitled to receive a royalty payment for every monolithic upper sold.

The 3 primary design concerns of monolithic uppers are as follows: 1: The entire upper receiver must be replaced if the handguard is damaged. 2: The entire upper receiver must be changed to change the length of the handguard.
3: The monolithic upper requires a mechanically disadvantageous long tubular barrel nut wrench to attach and replace barrels.

The Colt M5 handguard uses a design similar to that of the Seekins Precision Integrated Rail Mounting upper receiver or Aero Precision M4E1 upper receiver (both unpatented). The handguard mounts to an extension of the upper that surrounds the barrel nut. This system allows a nearly true free float, replacement of handguards, and ease of barrel replacement.

Charging handle

The charging handle used on the display model at Eurosatory 2022 was the Radian arms raptor (patent USD738452S1). It is unclear if this comes as the default option, other options are most certainly available.


The Colt M5 is an decent attempt to modernize the AR-15/M4 platform while showcasing innovations in the CZ Colt portfolio.

The name is a dead giveaway, the M5 was intended to be follow up to the M4. Unfortunately for Colt CZ Group, it appears the US Army may be replacing most M4s with Sig XM5s and the USMC may replace more M4s with HK 416s. This doesn’t make the Colt M5 completely dead in the water though, the fact that Colt CZ Group hasn’t gone bankrupt in the last 15 years increases their chances of getting government contracts from other US departments. Furthermore, this upgraded platform will likely be sold to state and local agencies that already have relationships with Colt. A semi auto version of the Colt M5 will probably be coming to market in 2022.