Heckler & Koch Mk23 - Tokyo Marui

I carried out a comparison test of theTM NBB Mk23 (against the KSC GBB) in 2003, but that test was written before I refined the reviewing process and, when I was loaned one by Airsoft Armoury to review for Airsoft International magazine, it seemed only sensible to record the results (and bring the photos up to date) here as well.

TM NBB replicates 'Phase 2' prototype as evidenced by cocking serrations on front of slide

In the Box

To a degree, the box is everything with TM's Heckler & Koch Mk23.

Cardboard slip case hints at contents

Inside the cardboard slip case, featuring details of the many features of the package inside, is a sturdy plastic gun case, bearing TM SOCOM Mk23 embossing on the lid. The catches look a little flimsy, being moulded plastic that bends to catch on the lower half, but overall it looks and feels solid and impressive.

Case is generally sturdy and looks good

Inside, the base is polystyrene and holds the gun and the accessories.

Everything is well secured and presented

As well as the gun, there is a Laser Aiming Module (LAM - which only fits in the case attached to the gun, but can be removed) and a 19CM long SOCOM silencer.

The usual collection of barrel cleaning rod and BB are also in the base and the magazine is fitted separately, although the gun cutout allows it to be stored with a second in the gun.

Under the eggcrate foam in the lid, there is a bag containing manuals, targets and a TM brochure.

First Impressions

The finish of the gun does, it must be said, look a lot like the spring pistol. This in itself is not bad, but the spring pistol retails for around £30 and the shiny plastic looks a little cheap on a gun costing around £105 (from Airsoft Armoury - www.airsoftarmoury.com - who provided this example for review). Even more disappointing for purists is the fact that the chamber and frame plate bear the same serial number as the springer, whilst the slide features a different number. Clearly the frame and barrel are from the same mould as the spring pistol, if not exactly the same parts.

The TM NBB looks very much like the springer in terms of plastic quality - Frame and chamber feature same serial numbers are springer, but slide doesn't...

Ignoring the finish, the Tokyo Marui Mk23 is a pretty decent gun. It’s very big (245mm long), but is quite light (you will decide if that is a positive) at 805g. Even with the LAM and silencer fitted it only just breaks the 1 kilo mark.

The Mk23 is a large gun, but the grip is ergonomic and surprisingly well suited to most hands

External metal parts include the trigger, hammer, safeties and slide lock.

Closer Look

TM chose to replicate a pre-production Phase 2 Mk23 for their NBB (Their springer is a replica of the production gun), but it differs only in a few trademarks and the presence of cocking ridges on the front of the slide, which were removed on the final design.

The slide is plastic, of course, but has a finish that looks a little like machined steel and features clear, deep markings in pretty much the right places.

The slide is marked "HK US-GOVT. Cal. .45" and "23-042" (followed by a small capital B in a circle) on the left side. On the right, the chamber is marked "HK Cal. .45" with 23-0499 and the B below it.

Slide lock and safeties are metal, but decocker is just moulded into frame.

The frame’s markings too, are well placed, but a few are Tokyo Marui where they should be Heckler & Koch. The grip is marked "Tokyo Marui Co., Ltd Made in Japan" at the top right. and "US SOCOM Mk. 23" at the bottom right. On the left, the grip is marked "HK .45" on the lower part. Under the front of the frame is a silver plate with the serial number "23-0499" on it.

The sights are well replicated, but are simply moulded into the slide and lack any markings, which would aid acquisition of the target.

Sights are unmarked and moulded into slide

The trigger, with a ridged face, is metal as is the hammer and both the working thumb safeties, but the decocker is simply moulded into the frame.

The ambidextrous magazine release either side of the trigger guard is metal and releases the big magazine, which accounts for 365g of the gun’s full weight and holds an impressive 28 BBs.

Seam under frame is prominent, but easier to tolerate on a replica of a polymer framed gun

One element of the SOCOM specification was the ability to fit a silencer and the Mk23 has a threaded barrel to allow this. The Tokyo Marui NBB’s outer barrel is mainly plastic, but features a metal threaded (in the real gun’s unique 16mm) muzzle, so there is little danger of stripping the thread; a thoughtful piece of design to allow long service.

Barrel end is metal, so fitting silencer won't strip the thread - Nice touch.

To most listeners a difference of 1 decibel is "just noticeable", 3 decibels is "clearly noticeable", and 10 decibels is "twice as loud", so the silencer reduces the sound produced by the Mk23 by very nearly 50%.

One great aspect of this gun is just how quiet it is with the silencer. In the open it is almost silent and even indoors, the sound of the BB hitting the soft backstop was louder than the suppressed muzzle report. With the silencer, the gun produced just 68 Db, compared to 76 Db without it.

The LAM isn’t as useful, producing a limited amount of light from the torch element, but no laser aiming effect, having only a red LED in place of a real laser.

LAM's light will dazzle briefly at close range, but 'laser' is just an LED

Sadly, both the LAM and silencer look a bit ‘budget buy’, with a glossy shine to the silencer (with TM trademarks) and cheap looking and feeling plastic mouldings for the LAM unit. That said, more realistic alternatives cost a large part of the cost of the whole Tokyo Marui package.

The Mk23 is a big gun, around 20 inches with silencer!

Shooting Impressions

Over 10 shots, the TM Mk23 averaged 325 fps (using Propane gas and .2g BBs) indoors (at 26C).

Experience suggests this would equate to around 290 fps at 20C, which seems low for a NBB, but is probably a result of the recent legislation restricting fps in Japan.

Shot      FPS
1 332.6
2 332.6
3 328.6
4 325.9
5 324.7
6 321.4
7 322.2
8 324.9
9 320.2
10 316.9

Trigger pull is heavy even for a NBB at over 3,000g. Fortunately, the pull is smooth and even and it doesn't affect accuracy or feel tiring when emptying a magazine.

Click on image for bigger version in separate window.

Carrying out my standard 5m/6 round, off hand test, the Mk23 proved remarkably accurate. With just my first 6 shots at a target, it produced a grouping of 5, 30mm across dead centre on the target.

I know I could have improved on that with a little practice, but 30mm is good enough for any purpose you would put a TM Mk23 to.

Many people report that the NBB Mk23 can outrange AEGs and at 70ft or so down my garden, it passed the 'Pig Test' (hitting a pig shaped target about the size of a postcard repeatedly) with contemptible ease.

One of the TM Mk23's claims to fame is it legendary silence.


The silencer is very effective, reducing the sound produced from 76dB (above) to 68dB (below) in my testing, which equates to a 50% fall in perceived volume.

Silencer fitted

Carrying out my FPS testing indoors with the silencer fitted, only the sound of the BBs hitting the bubble wrap back stop was audible.

Take Down

Field stripping is realistic, to a point.

Barrel and recoil assembly is unrealistic, but not all NBBs strip this far

After removing the magazine, slide the slide back until the disassembly notch in the slide (furthest forward on left side) is aligned with the front part of the slide lock and push the slide lock through the frame from the other side (you might need to get a finger nail under the slide lock and pull it through), completely removing it from the frame.

Once this is done, the slide, barrel and recoil rod will slide off the frame.

On the TM gun, the recoil rod, barrel and chamber are all one part and further disassembly requires tools.


Overall, the TM H&K Mk23 is accurate, powerful, efficient and has a range on a par with an AEG. You also get a great package with a useful silencer and good-for-looks LAM in a tough case.

Fullset looks good, but LAM for little more than show

For the price of a GBB you get the most usable skirmish gas pistol available and all the accessories you’ll probably ever need (spare magazines are widely available, too).

If you want a Heckler & Koch Mk23 to lovingly cherish, buy the KSC GBB. Otherwise, the Tokyo Marui is probably for you.

Weight : 805g (365g magazine)

Realism : ***
Quality : ***
Power : ****
Accuracy : ****

Real Steel link at World Guns
The H&K Mark 23 Owners Guild website - loads of information on the real Mk23.

Buy this gun at Airsoft Armoury

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