AEG rifles with blow back mechanisms are not new in the airsoft world. In fact we have seen G&G make their first electric blow back mechanism when they released their version of the L85 A1 and the ACM version of this made by Army Armament. The old electric blow back mechanism simply hooks the fake bolt onto the gearbox spring assembly thus mimicking the bolt action. It was impressive when it first came out but it was not long until we saw the negative effects this had on the performance of the rifle like shortened battery life and higher gearbox stress. In as much as some people would not accept this, blow back systems on AEGs is more of aesthetics other than anything else. So in my own opinion, if this system would interfere with the overall performance of the AEG then it is not worth having it.

I guess this is the same thing that G&G, one of the pioneers of electric blow back systems, saw on this certain blow back design and decided to develop a new and better system. Together with the release of their Top Tech line, G&G also released their brand new Pneumatic Blow Back System, The word “Pneumatic” mean “containing or operated by air or gas under pressure”. The new system is almost entirely independent from the main gearbox and makes use of compressed air generated from the main piston of the AEG to drive a smaller piston located on the top of the gearbox, which moves the fake bolt when the rifle is fired without adding any extra stress to the gearbox itself.

The T4-18

Packaging:

I have always been impressed with the way G&G present their products. I have had the opportunity to buy and own one of their most successful AEGs, the GR300. The Top Tech T4-18 is no exemption to this. The rifle came in a very impressive black shiny cardboard box with the picture of the rifle in front. Inside, the rifle is carefully placed on a hard foam material. The rifle and its accessories are well supported and protected from any damaged that transport and shipping may cause.

The packaged contains the following:

• The rifle
• 450 round hi-cap M4 style metal magazine
• Cleaning rod
• A special screw driver
• Operator’s manual

Externals

Typical to the old G&G tradition of making their airsoft replicas externally beautiful, the Top Tech T4-18 is no exemption. Overall, the rifle is solidly built and well balanced considering that the free- floating rail is made of full metal.

As we all know by now, the T4-18 is Top Tech’s version of the HK416. Why they called it otherwise could be due to trademark restrictions as initially rumored around various airsoft forums. And until its official release, it was called the Top Tech HK416 on some You Tube videos I have seen.

Aside from the name, Top Tech did a very good job in making sure that they capture the HK416 look with a few G&G special touches, which they are well known.

Here are the T4-18 vital statistics:

• Material: AL6061/ Aluminum Alloy/ Nylon/ Fiber/ Steel/ Zinc/ Plastic
• Overall Length: 780mm
• Weight: 3130g
• Inner Barrel Length: 375mm
• Muzzle Velocity: 90-100 m/sec with 0.2g BB
• Motor: 25000 rpm Hi-Torque
• Spring Guide: Ball Bearing
• Magazine: 450 rounds

To say that the T4-18 is a full metal AEG is an understatement. Externally, there are only two major parts that are not metal, the crane stock and the pistol grip. The rest are all made of metal.

The flash-hider is unique to this rifle. It is somehow similar to the G&G GR300, what I would describe as a “flashy” flash-hider, but only bigger. It also has a ring collar, which even makes it even bigger. One thing I was unable to do is detach the flash hider from the outer barrel, but, the actual outer barrel that sticks out from the front sight screws off revealing the end bit of the inner barrel. I suppose that Top Tech will come up with a short barrel attachment that you can just screw in. The only thing is, you will have to replace a shorter inner barrel.

The front sight is what I call the “half-ring” style similar to those found on some MP5’s. The front sight folds towards the front by lifting the locks found on either sides of the front sight shaft. The sight works and aligns well with the rear sight.  One complain I heard from other people is that the sight looks too thin and awkward when you look at it in comparison with the rest of the rifle.

Past the front sight is the “free-floating” front RIS hand guard. Well, it’s not really a pure free-floating RIS as it is held on the bottom rear end by a screw that goes through a “collar” on the assembly that attaches the outer barrel to the top receiver. The top rail of RIS connects perfectly like a piece of a puzzle to the top rail of the receiver giving the user a long continuous top rail. The front RIS assembly also acts the battery housing and it can be detached by removing the screw that I mentioned earlier, fold the front sight and slide the whole RIS assembly forward. The space inside the RIS assembly is very tight, as an ordinary mini 8.4v battery will not fit inside. The ideal battery to use is a single stock nunchuck-style battery, this look like a two short -stick type battery attached together by wires. Top Tech designed the outer barrel that is hidden inside the RIS very cleverly by putting grooves on each side to make the space for the battery a bit bigger. The wires used are the soft low-resistance type and Top Tech even threw in a fuse. They also placed connector on the wires that lead to the battery so that the wire will not have to be cut when removing the gearbox.

Now we go to the receiver. On first glance, the T4-18 receiver looks like your ordinary M4 AEG receiver, and it might just be as takedown is just the same as any other M4 type receiver but what makes this one different is that most of the levers and buttons that are sticking out of it a functional and not merely ornamental.

On the left side of the receiver you will find the fire selector switch. As with any other rifle of this type, it has three modes: “Safe, “Semi Auto” and “Full Auto”. Top Tech used the H&K symbols, which are the bullet drawings, to represent these three modes. The bolt carrier, which on the real rifle releases the bolt when it locks back, functions as a lock that will hold the fake bolt back when the charging handle is pulled for easy adjustment of the hop-up. On this side, you will also find the “MARINE ENV. T4-18” markings and the Marine ENV. logo. Underneath the logo are the markings “5.56MM NATO” pertaining to the rounds used by the real rifle. Below this is a serial number “T10005”. I am not aware at the moment I am writing this article if this is a unique serial number and if it is, this unit that was sent to us could be the 5th T4-18 made.

On the right side of the receiver, we will find ejection port with the dust cover. The dust cover pops open when the charging handle is pulled and when the rifle is fired. When open, the fake bolt can be seen and when this is locked back, the hop-up adjustment assembly is revealed. Just below the ejection port is the magazine release catch. The forward assist knob, which most of the times non-functioning on most AEGs acts as a spring release button when pressed. The marking found on this side of the receiver is the Top Tech Trademark logo and the words “TOP TECH” and “MADE IN TAIWAN”. Also, the fire selector on this side is also marked as it was on the other side and the button in the middle has a white line that rotates and points to where the fire selector switch on the other side is set. This makes me wonder if the gearbox that Top Tech used in this rifle is similar to the one used on SCAR replicas with their ambidextrous fire selector switches.

The magazine fits perfectly on the well. The magazine supplied is a 450 round hi-cap G&G magazine. This one also has the “5.56mm X 45” marking stamped on it. We also tried to use an ACM brand magazine with no problem.

The trigger is well fit and has no wobble. The pull is very crisp and the response is very good, not to soon but not too late. The pistol grip is a very nice as it is molded to the users hand. What’s even good is unlike other molded pistol grips, this one is ambidextrous and is comfortable to use with either hands.

On top of the receiver is the H&K type rear sight. The sight is full metal and functions very good. The sight is adjustable by windage and elevation. The special screwdriver that came with the package has a detachable part that is used to adjust the rear sight.

The stock is a crane stock and can actually hold a crane stock type battery. The wirings can be diverted with a little work to the rear of the gearbox to make use of the gearbox. On the other hand, since the rifle uses a nun chick crane stock type battery anyway, the stock can be used to store a spare battery.

The major markings on this rifle are painted on the receiver rather than laser etched as with other G&G rifles. And with personal experience, these markings are durable but will fade in time.

Internals

The T4-18 takedown is a straightforward M4 AEG takedown. To access the gearbox, the first step is to disconnect the two halves of the receiver. With the T4-18, all you need is to push the front disassembly pin out until it stops. The pin has a locking mechanism that prevents the pin from completely coming off. Once the pin is out, simply slide the top receiver forward. Do not forget to disconnect the battery wirings first.

Inside, the set-up is equally impressive. The lubrication is well placed and evenly spread. The wiring is the same type used with the battery connections. You also get 8mm ball bearings. The spring appears to be an equivalent of an M100 spring although we thought that Top Tech would have put a stronger spring as some of the air produced is diverted to the blow back mechanism. The connection to the pneumatic blowback is well sealed and no air leak was noticed. The ball bearing AL6061 piston head assures the user of smooth action all the time.

As the gearbox is similar to the Top Tech TM4 Carbine's, you can refer to more photos and better explanation of the gearbox and other internal parts in the review done by Optimus Prime and Bulletproofmike.

The motor, which they referred to as a 25000 rpm high torque is un-branded but I guess you will need a strong motor to produce enough power to run the blow back and still produce a respectable muzzle velocity.

The Hop-up assembly is plastic but works well and is marked with “G&G GR16”. I have read on forums that some airsoft manufacturers now prefer plastic hop-ups as the plastic is able to create a better seal therefore less air leak. The inner barrel has an inner diameter of 6.06mm, definitely something to replace when thinking of upgrading your T4-18.

Performance

Considering that the rifle is made mostly of metal parts, it is surprisingly lightweight. The rifle is more comfortable to shoulder with the stock fully extended and the crane stock provides extra comfort as a cheek rest when aiming.

Shooting is nice and crisp and the blowback makes a loud noise. You can’t feel the blow back but you will definitely hear it.

With the hop-up open, the rifle was able to produce a muzzle velocity between 325 to 338 fps.

Conclusion

The pneumatic blow back system is definitely a huge improvement from the flimsy electric blow back mechanisms of the past. This rifle is what we call as a strong buy product where most of its parts functions well. Raising the bar is just what the market needs and I think that this is just the beginning of the AEG blow back rifles that will be coming out of the market. But with Top Techs pneumatic blow back, other manufacturers will have a hard act to follow.

I would highly recommend this rifle as it is seldom that you get both good looks and realism on an AEG that you can actually use effectively out in the skirmish field.