Bolster Tuned CYMA CM.113B AKS-74U Zco Custom Upgraded AEG

The Original CM.113B AKS-74U Zco Custom

The basis for the Bolster Tuned AKS-74U Zco Custom Upgraded AEG is the CYMA CM.113B, a phenomenally built AKS-74U replica bristling with the latest Zco style furniture. With a steel receiver, fantastic quality aluminium external parts and high-speed internals with loads of potential, this was the perfect modernised derivative of the previously released Bolster Tuned CM.045 AKS-74U Upgraded AEG.

If you want to join us as we discuss the externals, read on, but if you are more interested in what Bolster Armouries have done on the inside of these bad boys, you can skip to the next section!

Starting at the front, we cannot help but notice the seriously intimidating DTK-2 muzzle break, constructed from steel and finished in flat black. One of the few flaws the Bolster Team noticed when inspecting the CM.113B is that CYMA had chosen the AK-105 version of the DTK-2, resulting in an offset mounting position due to the different location of the retaining detent. The original CYMA DTK-2 was switched out with the 5KU DTK-2, a version designed with the correct detent pin cutout for the AKS-74U and as such, the device now sits at the perfect angle. 

This muzzle brake is a big boy, mounting to the pre-installed 24mm CW Russian thread adapter fitted to the 14mm CCW male threads on the outer barrel itself. When removing the DTK-2, you'll need to hold the detent in the front sight down before turning it and when removing the 24mm CW thread adapter you'll need to remove the grub screw on the bottom. This allows any 14mm CCW threaded suppressor or tracer to be mounted without the need for extra adapters, nice if you're going for a sneaky Spetsnaz look!

Following just behind, we have the gas block/front sight assembly, finished with a mock anti-corrosion style coating matching real Russian AKS-74U rifles perfectly. The front sight can be adjusted for elevation using a front sight adjustment tool and is one of the few aspects of the iconic "Krinkov" silhouette that remains on this distinctive customised piece. On

Surrounding the barrel and gas tube, we can find the handguard which is CNC machined from aluminium and patterned after the real steel Zco B-11 handguard paired with a B-19 railed upper handguard. The handguard is significantly weight-reduced in classic Zco style, with angled vent ports furnishing the build with a lean 'n' mean look. Up top, we're equipped with a skeletonised 20mm Picatinny rail ideally positioned for mounting a PEQ or DBAL laser, or a tactical flashlight. The 6 o'clock position also features a 20mm Picatinny rail with a fantastic replica of the Zco RK-5 vertical foregrip pre-installed. The RK-5 is the perfect grip for a Zco build but can be swapped out for your preferred vertical or angled grip at your discretion.

On either side, we are equipped with Zco's unique negative space attachment slots, known as the "Basis" system. Basis works similarly to M-LOK, allowing you to directly mount Basis accessories or use 20mm Picatinny rail adapters. One short length of 20mm rail for the Basis system is included and pre-installed on the left side and can be removed or repositioned wherever you need it.

Mounted around the original AKS-74U open rear sight, we are treated to a detailed replica of the real steel Zco B-18 optics mount, providing a 20mm Picatinny rail which extends the full length of the rear sight housing. This rail is perfectly positioned to mount a micro red dot sight and you might even be able to squeeze a magnifier on as well, depending on your chosen mounting hardware. The B-18 is removable for those who prefer to use the classic open sights, though these can still be used as backup with the B-18 rail installed.

The receiver itself follows the standard AK-47/74 format with a centrally positioned ambidextrous magazine release at the front of the trigger guard, a mock bolt carrier on the right side of the receiver and a 3-position fire selector on the right side. The fire selector provides 3 modes of fire; safe, full auto and semi-auto, in that order. It is an AK after all! This was designed in to allow for fast selection of semi-auto with a quick sweep down of the selector, and isn't actually because the AK was designed for full auto, as is the common myth. This selector is also an extended design, featuring a welded-on extension to allow you to switch modes with your trigger finger without removing your hand from the pistol grip along with a cutout designed to allow the bolt to be locked back on a real steel AK.

To access the HOP-up unit of the AKS-74U Zco Custom, simply hold the charging handle back to reveal the alloy slider adjustable HOP-up unit. The slider unit is known as one of the best designs out there and that is the reason this unit has not changed in design since the original Tokyo Marui AK-47 AEG. To increase the HOP-up effect, simply move the slider rearwards. Returning the slider to the front will reduce the HOP-up to its lowest setting.

On the bottom of the receiver, we come to the pistol grip; an enhanced design inspired by the real steel Zco RK-3 grip, complete with finger ridges and dot texture to improve traction. This grip is quite a bit wider than the real steel version to accommodate the AEG's motor but perfectly carries over the Zco aesthetic. The trigger guard/magazine release assembly is realistically constructed from stamped steel, offering a centrally positioned paddle mag release which is easily accessed for both left and right-handed shooters.

Thanks to its Gate ASTER™ MOSFET, Bolster Armouries AOE Correction Washer and highly upgraded internals, the AKS-74U Zco Custom is ready for an 11.1V LiPo straight out of the box, great news for high rate of fire fans! We recommend an 11.1V 1200mAh LiPo in AK stick configuration for a perfect fit and excellent performance. To install your battery, simply press the button at the rear of the receiver top cover, after which it can be hinged open, revealing a Deans battery connector inside. With your battery installed, simply return the top cover to its original position and pull the charging handle to engage the locking button if needed, taking care to avoid trapping the wiring.

Over on the left side of the receiver, we have several authentic looking mock rivets, all in the right place for a visually accurate AK replica. Between the mock rivets, we also have the old-school Russian AK side rail, just in case you want a more rearward mounting position for magnified optical sights. This side rail is compatible with Russian optics with the appropriate mounting apparatus or 20mm Picatinny rail mounted optics using an adapter, though some adapters may need the B-18 rear sight rail to be removed.

Bringing up the rear, we are treated to what is probably the most adjustable rifle stock available, for the AK platform or otherwise! This stock is known as the Zco PT-1 and offers adjustable length of pull via the magnetic catch on the right side, adjustable cheek riser height via the bolts on the right side and an adjustable butt plate. Also present on the PT-1 is an ambidextrous sling bar for modern sling setups and an AK-style sling point on the right side for those who prefer an AK-style sling setup.

The adjustable butt plate allows you to set it up at the right height to suit your loadout and has been added in to allow the entire position of the stock to be raised, allowing for large night vision optics and thermal devices to be fitted and intuitively used. Like the old-school AK-74 side folder, the PT-1 can also be folded to the left side of the platform for storage or transportation using the button on the rear left of the receiver and returned to the deployed position by holding down the small silver tab on the underside of the hinge mechanism.

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The Bolster Tuned CM.113B AKS-74U Zco Custom Upgraded AEG

This isn't your usual "upgraded" AEG, where you pay for the parts and labour and the tech does only what they are paid to do. The Bolster Armouries tech team fully disassemble each of these AEGs down to every screw, bolt and bushing to perfectly tune the internals, polish the piston tracks and bearing holes, shim the gears to absolute perfection and replace parts to address the weak points in the original CM.113B. The Bolster techs treat these AEGs like they are building them for themselves, and if it doesn't pass their rigorous checks, which include a 60m accuracy test, it goes back to the bench for more work.

To replace the original Kestrel Basic ETU, the team have added the exceptional Gate ASTER™ ETU/MOSFET with the latest EXPERT Firmware to add some seriously advanced features to the CM.113B and kit it out to contend with the best. The ASTER™ boasts programmable fire controls through the Gate Control Station app, Gate Blu-Link or Gate USB Link, adjustable pre-cocking for a ferocious trigger response in semi-auto, cycle timing control, adaptive active braking, adjustable trigger sensitivity and voltage control, all of which combine to give this SMG-5 a wealth of functionality that is hard to beat.

Installing the ASTER™ requires modification of the gearbox shell and selector plate for compatibility with the ASTER's optical sensors. Copper is no longer used on the selector plate, and is instead replaced with an ASTER™ sticker to allow the optical sensors to detect its position, and adjust the fire mode accordingly. This has the benefit of being more reliable than a traditional selector plate, as the use of optical sensors takes corrosion which usually develops on electrical contacts out of the equation completely.

As you will receive it, the CM.113B is set up for pre-cocking in semi-automatic for a GBB-like instant response, and standard cycling in full auto so you can release the piston and prolong the life of the spring. These settings can be altered to your heart's desire using the Gate Control Station app, or a Gate Programming card, but there is no need to change settings as this AEG is set up to perform exactly as it should, and if there was a better combination of settings, the Bolster Armouries team would have used them.

Inside the gearbox, the Bolster boys have put in some serious elbow grease; modifying the shell to accept the ASTER™ ETU, sanding the piston tracks and bushing holes completely smooth to reduce every bit of friction possible, and shimming the gears to perfection for absolutely flawless functionality. The piston head O-ring has also been replaced with the Bolster Armouries Piston Head O-ring, providing a tighter fit than the original CYMA O-ring for improved consistency and air seal qualities.

The motor installed is the Warhead Base 27K Brushless Motor, offering a super speedy motor which uses high strength, SH-rated Neodymium magnets. Being a brushless motor, the Warhead Base simply doesn't heat up as the only friction generated inside is with the air, keeping this cool and allowing you to let off some seriously long bursts guilt-free. The Warhead moves the Bolster Tuned CM.113B up to the next level of Airsoft performance and puts it hot on the heels of the full-fat Bolster Armouries ONYX, ARKOSE, ATLAS and OBIRE builds.

To prevent known issues with standard ball-bearing bushings, Bolster Armouries added their own EZO Bearings, another part which features in the ultra high-end Bolster Armouries builds. Bolster Armouries EZO Ball-Bearing Bushings are designed and manufactured by Sapparo Precision Inc. in Japan and have been chosen by the Bolster team thanks to their extremely low friction, high-quality steel construction and fantastic reputation in a wide range of industries. These bearings allow the gears to spin freely at the tremendous rate provided by the Warhead Brushless Motor with minimal chances of failure, all while reducing stress on the gearbox shell and gear axles.

To maintain feeding reliability with its new Warhead Brushless Motor, the Bolster team opted to upgrade the tappet plate with the Laylax Perfect Reinforced Tappet Plate, a widely respected part from internal upgrade masters, Laylax/Prometheus. The Perfect Tappet is constructed from precision moulded resin with a low friction surface finish, ensuring you get the perfect blend of speed and strength. The Perfect Tappet Plate was subjected to a 30,000-cycle endurance test by Laylax prior to release, underlining the manufacturer's confidence in this superb reinforced component. 

Nothing beats a snappy trigger paired with a brushless motor and 13:1 gears! Being an AK platform, adjustable triggers are non-existent, but that didn't stop the Bolster team from working their trigger magic with the CM.113B. As used in the Bolster Armouries VULKAN Advanced AK AEG, the team installed the custom-made Bolster Armouries AK Trigger Spacer, reducing trigger travel considerably to the point that you can almost set it off with a gentle breeze. This makes the Bolster Tuned CM.113B a serious foe to contend with in CQB, able to put down rounds incredibly quickly with its ultra-short trigger pull and stunning trigger response rate! 

One of the biggest issues with mass-produced AEGs is the poor quality lubricant applied from the factory, in inconsistent amounts and in all the wrong places. Bolster Armouries has cleaned up inside the gearbox and applied Abbey Lubricant. This process alone makes a massive difference. Coupled with the internal enhancements, this Krinkov sounds more like an A-10 Warthog when it fires than an Airsoft AEG!

The CM.113B comes with a 6.03mm tightbore inner barrel pre-installed, but not being the types to trust Chinese quality control, the Bolster techs inspect every barrel for imperfections and give them a thorough clean and polish before reinstalling them. Even tightbore barrels can have internal flaws which affect accuracy when mass-produced, and the internal overhaul given to this AK guarantees that you will get a good, smooth barrel with a flawless inner surface.

While the stock HOP-up unit doesn't require the same enhancement process as the Bolster Tuned SMG-5, the team found the stock HOP-up bucking to be below the Bolster par. To solve this, the team installed the Maple Leaf Macaron 60° HOP-up Bucking, improving long-range performance considerably, both in terms of accuracy and maximum range. 

From a performance standpoint, this AEG is positively exceptional, being accurate to 60m and beyond, and ripping out BBs at a nauseating rate (for the other team, anyway!). When put on the chronograph this upgraded CM.113B spits out an incredible 26 BBs per second, beating the 25RPS of the previous version and neck and neck with the proper Bolster Armouries ONYX AEGs. FPS-wise, this AEG hits a very consistent 320 FPS when tested on 0.2g ASG Blaster BBs, but the Bolster Team recommend 0.28g BBs to make the most of the Maple Leaf Macaron HOP-up rubber. If you ever wanted a full-fat Bolster Armouries but cannot stomach the price, this is the next best thing!

The Bolster Tuned CYMA CM.113B AKS-74U Zco Custom Upgraded AEG benefits from the same decades of experience and careful hand-building process that the top-of-the-line Bolster Armouries builds do but takes advantage of the impressive stock parts in the CM.113B instead of replacing it all with aftermarket upgrades. It's amazing what talented technicians can do with a mass-produced AEG, some careful modification, a few choice upgrades and a world-beating ETU like the ASTER™!

Package Includes

• Bolster Tuned CYMA CM.113B AKS-74U Zco Custom Upgraded AEG
• 130rnd Mid-cap Magazine
• Speed Loader
• Bolster Armouries PVC Patch