Bolster Tuned CYMA CM.041 SD6 SMG-5 Upgraded AEG

The original CM.041 SD6 High Speed

The CM.041 SD6 is CYMA's sneaky SMG-5 variant, based on the real steel SD6 and complete with its integrally suppressed front end. Like the other CM.041 variants, this AEG boasts full metal construction for a realistic weight and feel, and is equipped with some remarkably impressive parts straight out of the box with but a few weaknesses which can be solved with the appropriate application of Airsoft knowledge. 

The SMG-5 SD6 has famously been used by every Special Forces unit you can think of, combining the original SMG-5's high rate of fire, extreme reliability and exceptional accuracy with an integrated suppressor which makes the real thing whisper quiet; perfect for eliminating lone sentries and guard dogs at the opening stages of a direct action mission. If you have a sneaky specialisation in game or you just love the looks of integrally suppressed SMGs this one is the best of the bunch!

Starting at the front end we can find the suppressor which perfectly matches that of the real thing in length, shape and profile. Unlike the real thing, this suppressor can actually be removed by turning the suppressor clockwise and removing it from its dual lug attachment. This opens up some interesting possibilities for a homebrew tracer unit, but we suggest not running the CM.041 SD6 without its suppressor due to how ugly it looks! Keep it the way the Germans intended; sneaky beaky!

Following the suppressor rearwards we come to the front sight assembly which mimics the conventional SMG-5 with its squared front sight post surrounded by an alloy protective ring.  This sight pairs perfectly with the rear rotary drum "diopter" rear sight, the sight setup which is often credited with being the best iron sight design out there. On the left side of the front sight assembly, we also have a built-in sling point, ideally located for use with the rear sling point and a two-point sling. 

The front sight is not adjustable, but the rear sight can be adjusted for windage by loosening the screw on the right side of the rear sight base and sliding it back and forth. The rear sight also offers 4 options for aiming apertures which range in size from the smallest, ideal for long-range semi-auto shots through to the largest which is great for close-range snap shooting, low light scenarios and full auto fire. 

The handguard follows the front sight and is the correct ribbed design for an authentic SMG-5 SD, providing plenty of grip and comfort for both left and right-handed shooters. The handguard is constructed from polymer but has a slightly different feel to the trigger pack, appropriately simulating the real SD6 handguard which is made from injection moulded rubber. The handguard also serves to reduce felt heat through the massive suppressor of the real thing which runs all the way back to the chamber and is built as part of the barrel itself. This is another part of the iconic SMG-5 SD6 silhouette and gives the CM.041 SD6 an authentic look. The handguard is held on by two pins, one on each side in the centre of the handguard.

What is known as the "cocking tube" lives just above the handguard, and as the name suggests, this is where you will find the cocking handle of the SMG-5 SD. The design of the cocking tube is slightly different to a conventional SMG-5 and includes linear grooves in the surface to reduce heat build-up for improved shooter comfort. 

The cocking handle can be pulled and locked up into its safety notch, as per the real thing, but this is not required to load the AEG of course. The cocking handle instead retracts the mock bolt carrier on the right side of the receiver, revealing the slider adjustable HOP-up unit. This unit allows you to increase or decrease the amount of backspin applied to your projectile, extending range and allowing the AEG to make effective use of BBs of various weights. The Bolster Armouries team have had their Waldo Customs greasy mitts all over this unit too; if you are interested in what they did you can read about it in the next section!

Moving rearwards we arrive at the receiver which follows the iconic SMG-5 format perfectly. The receiver is comprised of two parts, the upper metal section known as the “upper receiver” and the polymer lower section, known as the “trigger pack”. The fire selector is present on either side of the trigger pack and offers 3 modes of fire; safe, semi-automatic and fully automatic, with a 45-degree throw between fire modes. 

Each fire mode is indicated with the ever-recognisable red and white bullet pictograms which first appeared on the “Navy” style SMG-5 trigger pack and now make their way onto most modern platforms in one form or another. Safe is indicated with a crossed-out projectile in white, semi with a single projectile in red and full auto is denoted with several red projectiles. The fire controls of the Patrol Base X ASTER Edition can be programmed for burst mode, binary trigger and a plethora of other features which is a major step up from the original, offering you more options than ever before!

The grip itself is built into the trigger pack and is an ergonomic design with an enlarged trigger guard built in. This grip has been a subject of a lot of praise, and the shape and style match more modern platforms such as the AR36 and is widely credited with being the inspiration behind the highly popular MOE and MIAD grips for the M4/AR-15. The trigger guard allows plenty of space for gloved shooters, and the trigger of this, the Patrol Base X Gate ASTER edition has been swapped out for a flat SMG-5 trigger to give you the edge when it comes to laying down some rapid semi-automatic fire in CQB. 

The magazine release is also ambidextrous, being a paddle-style release positioned just ahead of the trigger guard, making the SMG-5 a fine choice for right or left-handed shooters. There is also a secondary magazine release over on the right side, on the magazine well in a similar position to that of the M4/AR-15. This gives you the option of two different magazine release styles, though we prefer the ambidextrous paddle release as the AR style release is a bit further from the grip than on an M4 and can be harder to reach for those with smaller hands.  

Running along either side of the receiver we can see a groove which is the track in which the sliding stock indexes, serving both to keep the stock tight into the weapon when retracted, reinforce the receiver and provide tracks for the bolt carrier to move along on the inside of the real thing. At the top, we have a pair of lugs which allow for an SMG-5/G3 claw optics mount to be added if you want to mount a red dot sight or scope to the CM.041 SD6. These lugs are compatible with both low profile and high profile options. 

The rear iron sight is located at the back of the receiver and is a rotary drum diopter-style sight, just like the real thing. The sight offers 4 different apertures for aiming, with the wider apertures being ideal for low-light situations and full auto fire, and the finer apertures are great for long-range shots and semi-automatic fire. Changing apertures is easy in any weather conditions thanks to the knurling at the top of the drum, simply turn the sight to the chosen position and it will lock into place under spring tension. 

In this, the Patrol Base X Gate ASTER Edition of the CM.041 SD6 we have swapped the sliding "J" type stock out for a fixed SMG-5 stock to give this beast a bit more battery space and improve the comfort of the platform. The fixed stock provides a comfortable cheek weld so you really make good use of the exceptional diopter iron sights and is equipped with a sling point on the left side to facilitate a two-point sling setup. The stock chosen is the same used on CYMAs CM.041B and is constructed from high density polymer with a high quality textured feel. Technically, this makes this AEG an SMG-5 SD5, but we will stick with the SD6 name so it is clear what the base platform of this build is. 

The CM.041 Patrol Base X Gate ASTER Edition

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.041 SD6. 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.

As with the SD6's predecessors, the team have added the exceptional Gate ASTER ETU/MOSFET to add some seriously advanced features to the CM.041 SD6 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 sneaky 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 SMG 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, and have modified the shell to accept the ASTER ETU, sanded the piston tracks and bushing holes completely smooth to reduce every bit of friction possible, and shimmed the gears to perfection for absolutely flawless functionality. The cylinder window corners have also been radiused, to get ahead of a known version 2 gearbox failure point by more effectively distributing the mechanical stress on the gearbox front from repeated impacts. The air nozzle has also been replaced with the Lonex air seal nozzle, complete with an air seal enhancing O-ring. The result is a system which is running at the absolute peak of efficiency, both electrically and mechanically.

As with previous Patrol Base x Gate ASTER SMG-5s, all of the internal parts of this CM.041 SD6 have been treated to Waldo Customs' delicious smelling silicone lubricant, both the THICC and SLIM variety. Waldo THICC lube has been applied to the cylinder head, and SLIM has been applied to the O-rings of the Lonex air seal nozzle and the piston head to prolong their life, enhance air seal qualities, and make them smell great!

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 doing this alone makes all the difference. Coupled with the internal enhancements, this SMG-5 sounds more like an A-10 Warthog when it fires than an Airsoft AEG!

When it comes to the HOP-up and inner barrel, the Bolster techs have worked wonders. One of the few complaints we have heard about the original CM.041 is that when fired in full auto extensively, the HOP-up unit tends to lose its setting and require readjustment.

To correct this, the Bolster techs have tightened everything up and replaced the polymer pin holding the unit together with a machine screw and bolt to ensure it remains rigid and effective. Naturally, these guys cannot touch an AEG without installing the phenomenal Prometheus Purple HOP-up bucking and nub inside, and of course, this CM.041 SD6 is no exception. This is what allows this upgraded version to nearly double the original in range, reaching out to an absurdly long distance for such a short-barrelled AEG.

The CM.041 SD6 comes with a 6.03mm tight-bore 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 tight-bore barrels can have internal flaws which affect accuracy when mass-produced, and the internal overhaul given to this CM.041 guarantees that you will get a good, smooth barrel with a flawless inner surface.

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.041 spits out an incredible 25 BBs per second, which isn't far off the proper Bolster Armouries ONYX AEGs. FPS-wise, this AEG hits a very consistent 347 FPS when tested on 0.2g ASG Blaster BBs, but the Bolster Team recommend 0.28g BBs to make the most of the Prometheus HOP-up rubber. If you ever wanted an ONYX but cannot stomach the price, this is the next best thing!

The CM.041 SD6 Patrol Base X Gate ASTER Edition benefits from the same decades of experience and careful hand-building process that the ONYX does but takes advantage of the impressive stock parts in the CM.041 instead of replacing it all with aftermarket upgrades. It's amazing what talented technicians can do with a mass-produced AEG and a few choice upgrades, some great quality lubricant, and a world-beating ETU like the ASTER.