The Colt M4 Carbine AR6951 is a 9mm semi-automatic rifle built on the AR platform with a 16.1-inch barrel and a four-position collapsible stock. At 6.35 lbs it handles easily, and the 32+1 magazine capacity keeps round count competitive with other pistol-caliber carbines. Colt includes ambidextrous lever safety and A2 front sight with folding rear sight as standard. 
 

Key Specifications 

• Brand: Colt Mfg 
• Model: M4 Carbine (AR6951) 
• Caliber: 9mm Luger 
• Barrel Length: 16.1 inches 
• Capacity: 32+1 rounds 
• Weight: 6.35 lbs 
• Stock Type: 4 Position Collapsible Stock 
• Action Type: Semi-Automatic 
• Sights: A2 Front & Folding Rear 
• Safety Type: Ambidextrous Lever Safety 
   

Features 

 
The collapsible stock adjusts across four positions for length-of-pull, which makes fitting the rifle to different shooters or shooting positions quick. Recoil in 9mm is mild compared to rifle calibers, so follow-up shots come easily. The folding rear sight folds flat when running an optic and pops up when needed without tools. 
 
The matte black finish is durable and holds up to regular range use. One practical note for buyers: this is a 9mm AR, not a standard 5.56 platform, so magazine compatibility and parts interchangeability differ from mil-spec AR lowers. 
 

Uses 

• Home defense: The light recoil and 32-round capacity suit close-range defensive work. 
• Range practice: 9mm ammunition costs less than rifle calibers, which encourages more rounds downrange. 
• Competitive shooting: The fast follow-up shots and manageable handling work well in speed-oriented divisions.

Owners of the Colt M4 Carbine in 9mm generally appreciate how light and easy it is to run at the range. The 6.35-lb weight gets mentioned often, and the mild recoil makes extended sessions comfortable for most shooters. The semi-auto action draws consistent praise for reliability.

The most common criticism is around accessories and aftermarket parts. Because the 9mm AR platform is less common than the standard 5.56 variant, some components require more searching, and not all AR accessories cross over directly. A few owners also compare stopping power with larger rifle calibers, though for the pistol-caliber category the 9mm is already well-suited to its intended role.

Overall the rifle gets positive marks for practicality and ease of use, with the parts ecosystem being the main friction point for owners who want to customize heavily.