The Heckler & Koch Mark 23 is a semi-automatic handgun chambered in .45 ACP, built around a cold hammer-forged barrel and a reinforced polymer frame. The Flat Dark Earth finish on the frame pairs with a black slide that carries a Maritime Coating for corrosion resistance in harsh conditions. 
 

Key Specifications 

• Model: Mark 23 
• Caliber: .45 ACP 
• Action: Semi-Automatic 
• Barrel Length: 5.87 inches (cold hammer-forged) 
• Capacity: 12 rounds (double stack magazine) 
• Weight: 42.24 oz. 
• Frame Material: Reinforced Polymer 
• Finish Color: Flat Dark Earth/Black 
• Sights: 3 Dot (front white dot and rear white 2-dot) 
• Threaded Barrel: Yes 
   

Detailed Features 

The Mark 23 runs a double-action/single-action external hammer system, so the shooter can choose their preferred mode. The controls are ambidextrous, accessible to both right- and left-handed users. A proprietary rail along the dust cover accepts lights or lasers. The threaded barrel accommodates suppressors and muzzle devices directly. 
 

Usage 

The .45 ACP chambering and 12-round capacity make it a reasonable choice for home defense or tactical training. It is large enough that concealed carry is impractical for most people, but at the range its grip geometry and sight picture are generally comfortable for extended sessions. Collectors also pick it up for its military-spec lineage.

Owners of the HK Mark 23 tend to land in one of two camps, though both groups respect the engineering behind it.

On the positive side, the construction quality gets consistent praise — the gun feels solid and holds up across varied conditions. Accuracy is a frequent highlight; shooters report tight, consistent groupings. The ergonomics work well for most hand sizes, even during longer range sessions. The threaded barrel and accessory rail are appreciated by anyone running suppressors, lights, or lasers.

The criticism centers on practical factors. The Mark 23 is large and heavy compared to most handguns in its class, which rules it out as a carry gun for most people. The price is a genuine barrier — owners acknowledge the quality matches the cost, but it puts the gun out of reach for casual buyers. Parts and model-specific accessories can also be harder to source than those for more common platforms.

Overall, the Mark 23 earns respect for what it is: a purpose-built, military-spec .45 that rewards shooters who want that specific combination of caliber, barrel length, and suppressor-ready design. The size and price are real tradeoffs, not flaws.