Knight’s Armament has a long history of innovation mainly due to Reed Knight’s wish to improve on anything that they make, the fact that he was close friends with Gene Stoner also helps as it would seem good ideas and common sense rub off between such great indivudials. The need for a PDW is as old as the shortened battle sword in order to make it handier and perhaps easier to use. The PDW type of weapon can trace it’s roots to the first attempt to make a regular machine gun portable during WW I. By the WW II SMG’s were used by troops in all the theaters but were deemed a bit under-powered due to the weak cartridges used. While rifles still dominated the battlefield, the birth of an assault rifle was the logical step. After WW II the assault rifle became and still is the main primary weapon for an infantry combatant. Although some still gravitate towards the battle rifle as the only proper tool for the job since it packs more punch over a longer distance, the need for a shorter, more compact weapon than the assault rifle is still present. By now an established fact, the SMG’s do not cut it in this particular role and shortened assault weapons tend to drag their own bag of problems with it, the PDW seems to be the answer. By size it would fit somewhere in between the SMG and the assault rigle although most PDW’s are of the same size as the SMG’s or slightly larger. The design and ergonomics came a long way since the M1 Garand was shortened and designated the tanker version. PDW’s use an intermediate round, which can be argued by some, that is simply not true, as some clearly see the 5.56 NATO round as the intermediate round. But let’s stick to what the majority of experts say, PDW’s use a round that falls into the category of intermediate rounds, which means, that just as the size puts them between SMG’s and assault rifles, so does the round used. To put things into a simple perspective, PDW ammunition is basically shortened assault rifle ammunition, well not quite, but it describes the basics of the concept.

For the KAC PDW, Reed Knight designed a special round with specific performance in mind. Since the PDW will not be used at long ranges (…up to 150m) the round was designed to outperform the 5.56 NATO round in almost all aspects up to the 200m range. It packs more punch, has better terminal ballistics, less recoil and all that from a 10″ barrel. Since the KAC PDW was envisioned as a weapon for specialized troops for close in work it would also be suited to being issued to troops who do not serve in the forward areas and front lines but still require a weapon of greater firepower and accuracy than a sidearm. Reed Knight also kept one more thing in mind as he designed the system (…and it is a system), its use and operation as far as the user is concerned should mimic the M14/M16 line of weapons as close as possible. Therefore the safety lever, mag catch, bolt catch, charging handle and the field stripping process are virtually identical to the M4/M16 line of weapons. They were “upgraded” a bit with ambidextrous controls and piston operated system instead of an direct impingement system, but other than that, it’s basically the same gun in a more compact package with a lot of bonuses. But keep in mind, the KAC PDW was never meant to replace the assault rifle, it never competed with the M4’s or their clones. As the name states it’s a Personal Defense Weapon that can handle assaults as well. Another thing to be mentioned, the KAC PDW has not been issued to any combat unit, it is not used in combat weapon, in fact it is by KAC still considered an experimental weapon and round and could be put into serial production if they land a Government contract. Until than, go visit some gun shows to get the chance to fondle a real one yourself.

Snap to the airsoft community… Personal Defense Weapons or PDW’s have been an object of admiration for airsofters since the first Marui PDW in the shape of the shortened and modified MP5 arrived at the scene. Quite a few of the PDW’s are available to the average airsofter, they come basically in three basic groups; GBBS, AEG’s and AEP’s. Even though airsoft is supposedly a game that mimics or emulates real combat, you will still see plenty of “snipers” using modified PDW’s, with P90’s with scopes and huge silencers, same goes for the MP5 PDW’s. But luckily, common sense is prevailing and PDW’s are seeing more use in skirmishes that emulate urban combat, in-door skirmishing, basically they are being used as they were originally intended.

The GHK KAC PDW we are testing here is the third incarnation of this GBB replica (…Version 3). It’s a fine example of good craftsmanship. Since we did not have the pleasure of testing versions 1 and 2, I’m not going to go into details over the differences between them. But according to GHK there are no differences between V2 and V3 (supposedly it was the shops that came up with the nomenclature and not them) while the V1 was an early model and was “modified” in a sense where the flaws were remedied thus V2 was born.

While it may not have all the bells and whistles of some of the competition GBB’s(…not that there is many competition for the PDW GBB’s), but the simplicity of it is remarkable and more than suitable if you use the replica in the way it was intended. We will cover this later in the review. The GHK PDW is an all metal GBB rifle with side folding stock, full monolithic railed front end/upper receiver, with flip up front and rear sights, full KAC markings (…they sure will not be happy about that, unlike the arsofters), full ambidextrous controls (…minus the bolt catch, that one is left side only). The replica uses a gas as a propellant, it’s capable of semi and full auto fire, it has a non-adjustable HopUp unit which can be modified in a short procedure and that’s basically it. Well not really, this was just a short description of the replica.

The first thing you notice when you open the box is the lack of styrofoam. Which is a nice touch if you look at it from the eccological standpoint, cardboard is bio degradable after all. The box contains the replica, with folded stock, the gas magazine, BB loader that looks like the small Marui one, but has a specially designed feeding lip that works with this particular magazine and a bottle of GHK’s excellent silicone oil. As is usual, silicone based oils are the ones to use in airsoft guns. And this being a GBB, more osil is to be used as only a properly lubricated GBB will function properly.

Starting at the rear of the replica, the stock is, as the rest of the gun, full metal, it folds to the right side, the front right side rail is cut short a bit in order to accommodate the folded stock. The stock locks into place when folded by a pin on the lower receiver. The pin locks into a special slot on the stock. The stock locks solid when extended by a sticky locking mechanism that sits at the base of the stock, where a stainless steel pin runs through it. The stock has a QD sling attachment so you can use your push QD sling attachment on it. The folding stock design is possible in this gun since there is no buffer tube to tame the recoil and movement of the bolt to the rear. This is taken care by a modified “piston” system with recoil spring mounted in the front of the weapon, located just before the bolt and bolt carrier. In the original this was solved by placing a single recoil spring between the two pistons that operate the action.

Moving on to the front, to the upper receiver. As I mentioned before it’s a monolithic design meaning that the upper receiver and the front pictainny railed portion of the replica are made from one solid piece. They are CNC machined and very sturdy. The charging handle is of a familiar design, known from the M4/M16 series, it is slightly modified to fit the shape and contour of the PDW, but is basically the same in concept. The top rail has a front and rear flip up sights mounted on it. The rear sight has a built in riser picatinny rail mount for smaller optics, that are popular at the moment. I’m talking about Aimpoint T-1 series, Docter red dots and Trijicon RMR’s These optics due to their size and shape require
a special mount that rises them a bit above the bore axis in order to get a proper cheek weld and sight picture. Just behind the rear sight, there is an indentation, a small channel grooved into the receiver that hides the rear sight a bit when folded down. The rear sight is adjustable for windage while the front sight is adjustable for elevation. The right side of the upper receiver reveals the ejection port which does not have a cover, nor does it have a shell deflector. The right side of the picatinny rails are cut short in
order to accomodate the folding stock. There is still enough of picatinny real estate present so you can mount an accessory there.

The lower receiver is ergonomically about the same as any of the M4/M16 so a familiar shape and controls placement should bring ease of use. The safety/fire selector is ambidextrous, the right side lever is however a bit modified, portion of it is cut, since most of the shooters are right handed and the lever in the original shape would interfere with the shooting hand/finger when in semi auto position. The magazine catch is also ambidextrous, which is a nice touch, the bolt catch however is only located on the left side. The rear of the receiver, just under the stock sports two push in QD slots, one on the left side and one on the rear, no right side slot is available. The slots are machined into the receiver and are not an add-on part as is more common with the M4/M16’s. The right side also sports a locking pin for the folding stock. The markings are true to the original, present on both sides. There is even an unique serial number on these replicas. Again a nice touch. The grip is formed after the real one, made of metal and is hollow. It’s somewhat small for my hands but the PDW is a small weapon after all so no grudge there.

The barrel is 10 inches long, it’s dimpled as the real steel version. Dimpling is yet another way to increase strength of the barrel, reduce weight and increase the area of the barrel to ensure better barrel cooling. The gas block is pinned to the barrel and additionally secured by two allen screws at the bottom. The barrel is free floated and it sports a replica of the KAC Triple Tap muzzle brake. The muzzle brake has a meta insert in it so it keeps shape since it has all the porting made to it to mimic the real thing. But since the real thing is made of super tough Inconel and this one of aluminium, the insert is there to keep it looking good even after you bump it into something. The muzzle brake has an indent at the front which is there for the purpose of securely mounting of the KAC QDSS-NT4 suppressor, well at least it is there for this reason on the real Triple Tap. Bottom line is the features have been copied in detail.

The magazine is GHK’s WA system magazine. Should be compatible with the WA type of GBBR’s but we could not make it work in the KA M4A1. The tollerances of the lower receivers seem to be a bit off between various manufacturers, so either some modifications need to be made to the magazine on order to fit them for use in other GBBR’s. According to GHK, their mags should work fine in Inokatsu GBBR’s, some with and some without any modifications. Bottom line, the compatibility is somewhat questionable. Not the best thing to find out, but what the heck, at least GHK builds their GBB’s to a certain standard, which to my experience is pretty high. The magazine sits in a M16 magazine shell, which kills the authenticity a bit, but nothing too serious. It does not leak, it does not suffer from severe cool-down and is all in all a very well made product. Loading it by hand is a pain since the spring is stiff, using a loader sure makes things easier. The magazine holds 40 BB’s and you can easily shoot two full BB loads on one gas charge if the ambient temperature is higher than 20 degrees celcius and you are using semi-auto mode.

Field stripping is done the same way as with the real weapon. Push out the rear pin, which is really stiff, so use some kind of a tool, screw driver or a pin pusher. But don’t push too hard, or you’ll just push it through. While the pin has a pin stop built in, if too much force is applied the pin will fly right through. As I mentioned before, the pins are stiff, which is a good thing so they don’t pop out. The bad side to this is you can not push them out without a tool. Anyway, for simply field stripping the replica for purposes of
cleaning and lubrication, just push out the rear pin and the replica will break open. You can than easily remove the complete bolt carrier assembly with the recoil spring.
If you want to perform further cleaning or maintenance, push out the front pin and the upper receiver will come off completely. The bolt carrier assembly and all the internals are according to GHK CO2 ready, which is a good thing since their CO2 magazine is about to come out. And even if you decide not to go with the CO2 magazine, internal parts will last long due to their CO2 ready design.

The upper receiver holds the barrel and the gas block in place. The barrel is secured by two large allen screws, which when unscrewed release the barrel with the gas blocks from the railed fore end. The PDW uses a standard AEG inner barrel and HopUp rubber. There is no HopUp unit that can be adjusted as the UopUp is fixed. You might go “hey wait a minute” now, but a fixed HopUp is not such a bad thing. Sure, you can not adjust it in order to get the longer shots, but remember, the PDW is a close range weapon and it does that well as we will cover that a bit later. The HopUp can be adjusted even though there is no adjustment knob or screw present. Simply remove the barrel and the HopUp rubber, replace it with a
rubber of your choosing and put some duct tape around it to create more pressure on the HopUp rubber that protrudes into the barrel. The process in not as fast and elegant as with an adjustable HopUp unit but is not that complicated and fairly fast. When dis-assembling the barrel gas block, make sure you don’t loose the return springs of the piston rods.

Aother thing that should be mentioned in regard to all GBBR’s, they cause more vibrations due to the nature of their operation, shaking things lose. So using a thread locker for all the screws might be a good investment. Use the blue Loctite or any medium strength thread locker so you secure the screws and still be able to un-tighten them if needed. The same should be done to some pins, but you’re gonna need to use superglue instead but not too much of it.

OK, we’ve covered pretty much all the internals and externals of the gun we’ve told you how the replica looks, feels, what it’s mechanical parts do and now we’ll tell you how the thing performs. GBBR’s are a new breed of airsoft replicas, even though GBB pistols have been around for a while now, the longer barreled GBB replicas are rather new compared to them at least these new ones that have no external power sources. GBBR’s being larger than the smaller pistol GBB’s requires larger inner moving parts as well as higher volumes of gas that will drive these parts and propell the BB through the barrel. This comes with its own box of problems. Larger parts mean more weight, more weight means stiffer springs that will return the action into the battery, this consequently means more gas that will be required to drive all these items. And besides the weight, players demand recoil, all this is achieved by mass, but heavier parts mean slower bolt movement. While this can be negated with a yet stiffer spring, you again need more gas… Do you see where I’m going with this? It’s a never ending circle, so a set of compromises is needed to make a properly working long barreled gas blow back replica. And GHK did a pretty good job with the PDW.

I explained all that because when you first cycle the action in the GHK PDW it seem somewhat sticky, especially if there are no BB’s in the magazine and the bolt locks to the rear and the charging handle ends up sticking at the rear. If you don’t understand the principles of how GBBR’s function and why they function the way they do, this might be a big turn-off. Same goes when you afterwards push the bolt catch, it all seems some sluggish, lazy. However a bit of silicone oil helps a great deal with is, additional knowledge of how things work get you even further.

There is a so called break-in period for all the guns, airsoft or real. Same goes for the GHK KAC PDW. It is made to tight tolerances and this requires a break-in period of at least 25 magazines before it functions flawlessly. You can speed up the process by goofing around with it and pulling the charing handle a few too many times. GHK assured me that this will not break anything but it will smoothen out the edges and rough surfaces and help the GBB to function smoothly and without any malfunctions. So, keep in mind, to break in the replica before taking it out into the filed and judging it. An AEG usually requires for the HopUp to break in but is otherwise ready to go out of the box, this does not seem to be the case with GBBR’s, at leadt not with this one.

Another crucial issue applies to the GHK’s PDW, maintenance… Same goes for all replicas, but GBB’s & GBBR’s are a bit more demanding in this department. Lubrication is essential, however the manual that is included with the PDW hardly covers this part. Which essentially means you will have to be extra careful and some creativity and find information on the web on what exactly you will have to lubricate, how often and what with. Actually, the last part is clear, you use their silicone oil. However if you are not carefully, O-Rings on the bolt will start leaking and performance will suffer. For this reason, take a look at the short instructional video on how to replace the O-Rings on the bolt. I have a funny feeling folks will be doing this a lot, since I have a vague idea on how meticulous people are when maintenance of airsoft replicas comes to mind. The kind folks at GHK made this instructional video for this reason.

Charging the magazine is simple, the gas charging nozzle nozzle is located right next to the release valve, at the back of the magazine, charging the magazine with gas is un-eventful. No leaks, no drama, the magazines take just about any gas you can find. Loading the BB-s is best done with the BB loader that comes with the gun. Inserting the magazine takes some getting used to. First the magazines are heavier than your garden variety AEG mags. Second, the finish on the replica, the mag well fit and the magazine finish require you to use some force to insert the magazine to seat properly. Tap the mag to seat it securely. Once the finish on the mag catch, mag well and the magazine has worn off a bit, once the gun broke in, things get a lot smoother. Same goes for the charging handle, once the gun has been through a few hundred BB’s and as long as it’s properly lubricated it becomes the smoothest firing GBBR I’ve had the pleasure of firing, OK, not counting Clarence Lai’s masterpieces. The sounds and the feel of the action are rewarding after that. The recoil is strong and the bolt is fast. The springs return it into battery quickly and follow-up shots are quick and crisp. The trigger seems to be of too stage design with not too
much over travel, no crisp, almost crisp. The report is loud, so a suppressor will more or less ad cosmetic value but will not lower the noise signature. Flicking the firing selector to full auto and pulling the trigger will bring a wide grin to any man’s face, as long as they are airsofters, make no mistake there. There is some vaporisation visible through the ejection port on prolonged full auto bursts, but all seems to be withing the tolerable gas consumption and performance. The bolt catch is a working one, which as is usual with all the GBB’s is a bonus as far as realism is concerned, however it can be a downside if you prefer to goof around with it and would much rather see the bolt cycle even without BB’s in the magazine when “dry firing”, with only the gas in the mag. However, this being a more or less standard Armalite ergonomic design with all the controls in the usual places, this can be quickly “remedied” as you only need to hold the bolt catch while firing and the bolt will not lock to the rear when no BB’s are loaded into the magazine (…or when they’re expended) either way, goofing is ensured.

We tested the gun at an ambient temperature of about 23 degrees celcius, gas was Begadi’s Power Gas, and we used Madbull 0.20 BB’s and it clocked between 305 and 320 FPS. Semi auto shots were pretty consistent at about 310-315 FPS. Fps fell if we used fas following double-taps to 305 FPS or if we used longer bursts on full auto. All in all the FPS was consistent and more or less as expected. Luckily we had more than just one magazine to use with this replica, so ammo dumps were performed and no real hicups or malfunctions were observed, except a few operator mistakes, when changing the magazine and cycling the action.

The fixed HopUp unit received mixed marks. While mostly using AEG’s you expect to adjust the HopUp and get decent range even with 300something FPS replica. The PDW does not have this option, so choosing your gas and BB weight will greatly determine your point of impact and your BB’s flight pattern and range. The HopUp is designed to work best with BB’s that weigh between 0.20 and 0.25g, the effective range of the GBBR with those BB’s is 30m max, however at 20m the accuracy and grouping is impressive, making this a perfect CQB/CQC skirmish weapon.However we replaced the original HopUp rubber with an aftermarket one and added some duct tape just to see how the performance will change. Mind you, there is no actual need for changing the HopUp rubber, it works well with 0.20, 0.23 and 0.25g BB’s. Anyway, after we did that, we could easily use 0.30g BB’s and consistently hit a 10cm circle at a range of 25m on semi auto. I believe once the CO2 magazines will become available, range will increase and you should be able to use heavier BB’s at longer ranges.

So, what is the conclusion on the GHK’s KAC PDW? It’s reasonably priced it does have a fierce competitor in WE’s KAC PDW, how do they compare? Not sure, still waiting on the verdict. Simply because it’s short, handy, works well and has nice features. Is it a good skirmishable replica? Not as much as it would like to be, the lack of range is a problem if you want to use it outside the CQB/CQC arena, the consistency is a problem as it is with most gas powered replicas. Other than that, it’s perfec toy to play around when you have nothing better to do. If you have an indoor skirmish site, it’s a safe bet, if you like doing fire drills, it should excell there as well. But it is not a main skirmishing replica after all. It has no dead serious flaws, and if you consider all the facts about it and use it accordingly, it will not let you down.

Test item provided by Test item provided by GHK Airsoft

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