King Arms PDW SBR In-depth Review

[AK47frizzle]

Hello there chumps.

 

Are you into the pistol caliber craze? Do you want something this is lightweight and practical? Do you want something that is better than the ARP9, lookalikes, and everything else in its price range? Then, this is the one for you. Allow me to explain why: 

 

Introduction

 

So, I stumbled into this weapon not too long ago: https://www.evike.com/products/89987/ And, I was thinking to myself: "wtf is this". I'm sure most you would think that. It is a cross between an M4 and an MP5, using an M4 body contoured towards using MP5 mags. This creates a rather unique aesthetic, one that I grew to enjoy over time. I then discovered this version: https://www.evike.com/products/94439/ A grey bodied SBR with an MLOK rail and silencer. And holy shit, this thing was cool. They are also only around 2kg! Ridiculously lightweight. Perfect for fast and lightweight-geared players like me.

 

As I waited to gather funds, this thing eventually released in the UK and EU. Specifically, the black MLOK and silenced version from Taiwangun: https://www.taiwangun.com/en/electric-3/pdw-sbr-sd-black-king-arms?from=listing&campaign-id=14&q=pdw+sbr No, this isn't the cool grey version that I wanted. However, it still looked pretty cool and classy in black. For only £160.52, this competes against all those CYMAs, NUPROLs, Specna Arms, G&G Combats Machines, and the infamous G&G ARP9. Cool looking, cheap, practical, and compatible with generic parts. It was a no brainer that I bought it as soon as I had the funds available, as well as a few CYMA 120rd mid cap mags. This totalled around £200. Patrol Base also has them and sell for £180: https://www.patrolbase.co.uk/king-arms-pdw-sbr-sd-assault-rifle?pv=10344 This is more expensive, even with shipping. And, they do not have the CYMA MP5 mid caps; only the high caps. 

 

With the miracle work of UPS, the package arrived in once piece:

 

 

I had already removed the packaging earlier from excitement. It was wrapped in black plastic wrap with a lot of rounds of bubble wrap underneath. Pretty well protected by Taiwangun.

 

Opening its contents:

 

 

More bubble wrap to secure it in place. Respectable. Removing that further:

 

 

What a clean beauty. No problems or missing items. Although:

 

 

This tag is telling me this gun is shooting too hot for most UK sites. Seems like I will have to downgrade it before I can use it.

 

This is what the small bag off goodies contain:

 

 

2 different backstraps for the grip and a flat price to replace the bump on the front. I tried on a few and I quite like the smaller backstrap: 

 

 

Though, I will keep the standard one on for now.

 

External Feel

 

Picking this gun up for the first time, it felt incredibly light which was not surprising since it has a plastic body. It has a metal MLOK handguard, not plastic unlike most people say. The plastic body has a matte finish and does not feel cheap at all. The metal handguard is smooth and has a solid feel to it. The trigger is flat and metal, giving good leverage. The stock is plastic, retractable, and does not rattle or move around when shouldered. The stock tube is also plastic and has a decent amount of space for a large lipo. The metal rods that lock the stock in place are metal with a matte finish. 

 

 

Personally, I was not planning to attach anything to rails, so I removed them to reveal the smooth and straight rail:

 

 

The rails are easily removable using a metric 2.5 hex key.

 

It has an odd but understandable design on the other side:

 

 

It is essentially an M4 body, and all they did was overlapped the forward assist area until the dustcover matched an MP5 ejection port size. Quite hilarious but logical to be honest.

 

Pulling back to charging handle:

 

 

This reveals a traditional, and shitty imo, hop up chamber. Nothing special. It does not lock back; the bolt release on the other side does absolutely fuck all.

One small problem that I immediately noticed is that the o-ring for the silencer seeps out like a fat guy's beer belly splurging out of his t-shirt and over his trousers. Not a pretty sight:

 

 

I tried realigning it several times. But, it became clear that it just would not sit properly. So, I removed it and that was that.

 

Additionally, there seem to be small tolerance issues with the body:

 

 

 

The upper and lower don't quite align exactly. However, it is still sturdy and does not rattle when handling. Therefore, this is acceptable to me.

 

The handguard wasn't exactly straight out of the box also. I rectified this by removing the handguard by the 4 screws and clamping the rail and body together using a red dot:

 

 

I then reinstalled the screws and it appeared much better:

 

 

Next, I had a go at fitting and comparing the magazines:

 

 

On the left is the King Arms magazine, and on the right is the CYMA. The quality in build difference is noticeable: the King Arms feels like a flimsy bit of plastic, and the CYMA is much more sturdy in comparison. The King Arms magazine is also slightly thinner than the CYMA. This naturally meant that the CYMA magazine was a tighter fit. However, it works just fine with a bit of breaking in:

 

 

Weighing the gun:

 

 

2042g without a mag.

 

 

2120g with the King Arms mag.

 

 

And, 2188g with the CYMA mag. Overall, super impressive weight. Around 2.2kg with a battery, mag, and BBs, is an incredibly practical package. 

 

Getting to the battery compartment meant removing the stock:

 

 

To remove the stock, there is a large button under the buffer tube that you press to release the positioning of the metal rods. When it is at its extremity, you need to push down the button as shown in the photo above to get it completely off. A small buffer tube cover is then revealed and is it super intuitive to remove:

 

 

The battery space is fairly generous and should fit the vast majority of lipo sizes out there. 

 

Test Fire

 

Unfortunately, it is a tamiya connector. So, uh, gimme some time to zip back to early 2000s and back:

 

 

So, this is how it sounds out of the box using a half-charged, 9.6v 1600mAH NiMH battery without adjusting anything:

 

 

Not bad at all. Definitely sounds better than your average midrange AEG out of the box. Fire rate isn't too shabby. But, a bit sluggish for my taste. The foam-filled silencer does make a noticeable difference in sound.

 

Now, onto the chrono. I used 0.25g Amoeba BBs which was what I had at the time:

 

 

 

 

 

 

So, out of the box, definitely too hot. The fps also kept decreasing into the borderline 300s, and I confused as to why until I remembered that this gun has the shitty traditional style hop up. It slowly unwound itself over time. The hop up chamber definitely needs to be tightened. OR, you save yourself the pain and get this for £8: https://www.ak2m4.co.uk/zci-prowin-style-hopup-chamber-plastic-m4?search=zci This style of hop up is vastly superior because it is easier to adjust and more importantly, it is similar to a worm-gear style design where it cannot unwind itself.

 

 

Overall, nothing special which was to be expected with stock performances.

 

The Deep Dive Into the Internals

 

WooOOOoooOoOOooOoo... Time for some spooky voodoo stuff.

 

Disassembly is just like any generic m4. Simply remove this first pin at the front of the receiver:

 

 

This pin just falls out; there is no pin in the receiver to hold it in place like many other M4 AEGs.

 

Pulling apart reveals the gearbox:

 

 

And like a regular M4 AEG, the hop up and barrel assembly is housed in the upper receiver.

 

The hop rubber looks like a traditional nub:

 

 

Nothing special and gets the job done. The barrel is also very clean too. Websites say that it is a polished 6.05mm brass barrel,

 

Comparing to my custom M4 AEGs: ZCI rotary chamber, 229mm ZCI steel barrel, maple leaf macaron and omega nub:

 

 

If I were to install the custom M4s hop assembly into this gun, the foam sound would be more pronounced as the stock inner barrel does protrude quite far into the silencer:

 

 

Removing the stock is pretty easy, just like a standard M4:

 

 

Removing the mag release requires a metric 1.3 hex key:

 

 

You do not need to remove the MP5 style mag release to disassemble the gearbox.

 

The body pin and rear gearbox pin comes out with a pin and a hammer:

 

 

Then, the motor grip:

 

 

Comes out as expected:

 

 

The motor does not have any markings. I can also turn the pinion very easily which indicates that it is not very torquey.

 

After all those components are removed, the gearbox can be pulled out:

 

 

Looking inside the lower receiver, seems to be just as high quality:

 

 

Then, I was pleasantly surprised by something:

 

 

Quick change spring! This feature is a godsend as it makes the assembly process so much easier. And, as you can see, there is a small unit just below which is the mosfet.

 

Taking it out, however:

 

 

It's stuck... the spring is attached to the piston which is a bit of a lame move 😕

 

Nonetheless, the gearbox disassembly is a straight forward process since it is just a standard V2:

 

 

And revealing its contents:

 

 

The trigger spring is incredibly stiff, more so than normal. I do enjoy the red colour scheme. The contrast provides some nice eye candy.

 

A close up on the mosfet unit:

 

 

It stays in place with a single screw and does not wiggle at all. And as you can see, the grease is very stringy on the gears. Not very nice to be honest. Spinning the gears makes it look like I'm weaving silk. The gears are standard 18:1 and of decent quality. I can't comment on durability yet, or ever. Because I will be changing them out to create a high-speed build. This guy preaches about it though: 

 

 

 

Gearbox has a nice gap here to push the anti-reversal latch if the gearbox ever locks up:

 

 

Testing the compression:

 

 

It is excellent. I can't push the piston forward with my finger over the nozzle. Genuinely amazing seal for a stock gun of this price.

 

What the stock AOE looks like:

 

 

Not great. But, the standard for stock AEGs. Should last a good while like this, assuming everything else is stock.

 

Setup to test the stock shim job of the gears:

 

 

Testing the sector gear:

 

 

 

Has more than 0.5mm of travel. Leaves a bit to be desired.

 

Spur gear:

 

 

 

Seems to be about more of less 0.3mm of travel. Not too bad for stock.

 

And for the bevel:

 

 

 

Seems to have about 0.1 - 0.2mm of travel which is excellent for stock. Overall impressive.

 

The gearbox is even radiused at the top and bottom:

 

 

Now for the spring... it is attached to piston and requires a very long screwdriver to get out. Otherwise, you fight the spring tension which isn't nice (excuse blurry photo):

 

 

Which reveals a disc:

 

 

This is easily popped out with a bit of force:

 

 

However, you will need the disc when reassembling the piston. Otherwise, the piston head will be loose.

 

 

The reassembly is super smooth too:

 

 

The anti-reversal latch does not pop out like a maniac, unlike most V2 gearboxes. And, with the quick-change spring, I don't even need to hold anything down when putting the other half back on. This makes reassembling incredibly easy and pleasant to work on.

 

This gearbox is super impressive. By far and large, one of the best gearboxes for the price. This is even better than some of the higher up, premium price tag stuff.

 

Quick Comparisons

 

At £160.52 currently, this is roughly around the prices of many Combat Machines and Specna Arms rifles. I cannot comment on Specna Arms as I have not used one before. However, G&G Combat Machines I have. I have also wielded the ARP9 myself which is its direct competition which I will be mainly comparing it to.

 

If we start with combat machines, I recently worked on one of these which are very common rifles: https://www.patrolbase.co.uk/g-g-combat-machine-cm16-raider-2-0

 

They are decent guns for the price. However, the gearboxes are of lesser quality in comparison: no mosfet, worse shimming, worse compression, worse piston quality, no anti-reversal hole. The barrel quality is also worse. Cannot comment on the gears, but I'd imagine they are similar in quality. The overall construction is tighter on the King Arms compared to the combat machines. King Arms have been known for their tight construction, especially on their higher-end guns. Maybe not all bells and whistles since the construction on their MDT LSS, that I had for a while, was so tight that some parts of the metal had to be cut with a dremel to disassemble the gun...

 

Now, compared to the ARP9, the definitive reasons to get the PDW SBR over the ARP 9 are:

 

• Gun itself is cheaper
• Bigger battery space 
• Mags are significantly cheaper
• Midcaps hold more rounds (60 vs 120)
• Less crazy, space-gat looking than the ARP9

 

Of course, not to say that the ARP9 is a bad gun. It is definitely a gun that is good, popular, and worth the price that it is at. It's just that these features of the PDW SBR (the looks got me tbh) make me prefer it over the ARP9.

 

 

Verdict

 

Time to list some pros and cons.

 

Pros:

• Cheap, entry-level price
• High-quality plastic and metal construction (SD version)
• High-quality gearbox
• Quick change spring
• Lightweight
• Short
• Customizable grip
• Compatible with most conventional V2 parts
• Super cheap extra midcap mags
• SD version has a cool foam-filled silencer
• Polished 6.05mm barrel

 

Cons:

• The mag that it comes with is flimsy and a loose fit
• Weak motor
• Shoots hot out of the box
• Some small fitment issues

 

Overall, this is a top recommendation. For the price you pay (£160-ish), this thing punches so far above its weight, and it is an incredible base for a high-tier performing gun due to having a standard V2 gearbox and a normal M4 hop chamber. There are only a few rifles I can think of that can compete against the PDW SBR in terms of practicality: one being the ARP9, another being the ARES pistol M4 series. I have yet to get a hold of the ARES gun, so I cannot comment on that. However, I have seen decent DSG builds which utilize the ARES ETU.

 

This is my new main weapon now. Gotta upgrade the shit out of this thing, internally. Externally, gonna keep it mostly stock to minimize the weight. A red dot with a riser at most.

[AK47frizzle]

Found out a crucial problem. It does not take these style hop units very well: 

 

 

The stock king arms one looks very similar to this:

 

 

The reason why prowin style does not work very well is that the magazine can move back and forth a bit in the mag well. If it is fully rocked backwards, the bbs don't feed properly and results in low fps - I was wondering why I had 100-150 fps on a 0.25g sometimes after installing one of those. The reason why the stock one works is that the square base plate at the bottom of the hop sits lower compared to the prowin style. It is also wider which limits the rocking too. I guess the solution is just to leave it unless you are buying an upgraded version of the same style. I personally prefer the rotary system of the prowin style. However, I guess I will have to settle with this.

 

Mine currently works like this after upgrades:

 

 

30 rps fuuuuunnnn

[Cipher-032]

Thanks for the indepth look.

I had a Prowin unit out of my G&G, with a R hopped Prommy barrel. I chopped it down, and fit it. I did get the odd misfeed, but I found after lubing the magazines it works a treat now.

Doing that will allow a small drop in FPS, hops .28's like a champ, and will allow better use of the suppressor or a tracer unit.

I really like how short it is, and how light and nimble it is. But I really must buy a high torque motor for it. So im debating a SHS high torque or a Nuprol one to keep costs down.

 

[LoneTactix]

I just bought one of these and test fired it last night. It seems to shoot well enough, but the consistency of accuracy seemed a bit off - some dip a bit, some fly straight as an arrow and some drift up a bit. I am wondering if this is normal for the gun as stock or whether the hop is a bit poo, or maybe I just don't target shoot much as I just skirmish my guns and don't really analyse them in depth.