Heckler & Koch Mark 23 – .45 ACP, 5.87" Barrel, Two 12-Round Magazines (81000078)
The Mark 23 is HK’s commercial counterpart to the U.S. Special Operations MK 23 MOD 0 — a full-size .45 ACP DA/SA pistol built for match-grade accuracy without hand-fitted parts. This configuration ships with a 5.87-inch threaded O-ring barrel, polygonal bore, and two 12-round magazines. HK part number 81000078, UPC 642230261587. This listing is for the Mark 23 with two 12-round magazines only.
Threaded O-Ring Barrel and Polygonal Bore
HK publishes a 5.87-inch barrel with a 1:14.88" twist (378 mm twist length). A high-temperature rubber O-ring seals the barrel in the slide until unlocking; HK states the O-ring lasts beyond 20,000 rounds and is operator-replaceable without tools. The barrel is threaded for suppressor-compatible accessories, and the polygonal bore profile is intended to support velocity, service life, and easier cleaning.
DA/SA Controls You Can Actually Run
- Frame-mounted decocking lever separate from the ambidextrous safety — lower the hammer quietly from single-action without flipping the safety.
- Ambidextrous safety lever for cocked-and-locked single-action carry when set to Safe.
- Ambidextrous magazine release and an extended slide release.
- Match-grade trigger feel on a DA/SA hammer-fired action (SA approx. 4.85 lb; DA approx. 12.13 lb per HK’s operator manual).
- Patridge-style sights adjustable for windage and elevation, standard 3-dot.
- Universal mounting grooves on the frame for accessories.
- U.S.-delivered Mark 23 pistols after 1999 include HK’s patented Lock-Out device.
Size and Weight
Overall length is 9.65 inches, height without magazine 5.90 inches, frame width 1.58 inches, sight radius 7.76 inches. Weight with an empty 12-round magazine is approximately 2.66 lb (1.21 kg) per HK’s operator manual.
Heckler & Koch Mark 23 Specifications
| Manufacturer | Heckler & Koch |
| Model | Mark 23 |
| Part Number | 81000078 |
| UPC | 642230261587 |
| Caliber | .45 ACP |
| Action | DA/SA, short recoil, modified Browning linkless |
| Barrel Length | 5.87" |
| Twist | 1:14.88" (378 mm) |
| Barrel | Threaded O-ring barrel, polygonal bore |
| Capacity | 12 rounds |
| Magazines Included | Two 12-round |
| Overall Length | 9.65" |
| Height (w/o magazine) | 5.90" |
| Frame Width | 1.58" |
| Sight Radius | 7.76" |
| Weight | Approx. 2.66 lb with empty 12-round magazine |
| Sights | Fixed patridge, adjustable windage & elevation, 3-dot |
| Trigger Pull (approx.) | SA 4.85 lb; DA 12.13 lb |
| Frame | Fiber-reinforced polymer |
| Slide | One-piece machined steel |
| Safety | Ambidextrous safety, decocker, firing pin block, Lock-Out device |
Frequently Asked Questions
How many magazines ship with 81000078?
HK lists this ID as Mark 23, .45 ACP, DA/SA, two 12-round magazines.
Is the barrel threaded?
Yes. HK publishes a threaded barrel with O-ring lockup and a polygonal bore profile.
What is the twist rate?
HK’s operator manual lists twist length 378 mm (14.88 in.) — a 1:14.88" twist.
DA/SA or striker-fired?
This is a double-action / single-action hammer-fired pistol with a separate decocker and ambidextrous safety.
Internal Reference:
81000078
Barcode:
642230261587
| Brand: H&K |
| Model: Mark 23 |
| Caliber: .45 ACP |
| Capacity: 12 |
| Firearm Action: Semi-auto |
| Barrel Length: 5" - 6", 6" |
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This item cannot be shipped to the following locations due to legal or carrier restrictions:
Restriction Details
This product cannot be sold or shipped to your location due to magazine capacity restrictions. Magazine capacity cannot exceed 10rd. If you believe this to be incorrect or if you're exempt from the restriction, please contact us at 636-791-1655.
Affected States/Territories (10):
Restriction Details
Vermont restricts rifle magazine capacity to 10rd. This exceeds the state's restricted capacity. If you believe this is in error or if you are exempt from the restriction, please contact us at 636-791-1655.