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Boyi DBoys M4 CASV Airsoft Gun AEG Rifle

Boyi DBoys M4 CASV Airsoft Gun AEG Rifle
$129.95  per EACH
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Item Code: ERM-BI-M4-3581
Airsoft Guns Styles: M4 Airsoft Rifle
Airsoft Manufacturers: BOYI CYMA
Model: M4 CASV Airsoft Gun AEG

- Boyi D-Boys M4 CASV Airsoft AEG (Airsoft Electric Gun) Rifle
- 320 - 350 fps (0.2 g BB)
- Integrated RIS System with Top Rail and Foregrip
- 300 Round Hi Cap Magazine Included
- Forward Grip Included
- Battery and Charger Included
- 3 Point Tactical Sling Included
- Adjustable Front & Rear Site
- Adjustable Hop Up
- Mostly Metal Body & Metal Gear Box
- Airsoft Gun Review & Airsoft Upgrade Video Available - Click More Info
- Made in China

The S-System has long upper rail, side rails and bottom rail that can accept both airsoft and real accessories. Rails are metal made while the system frame is plastic. The method how the S-System is locked to the gun is simple and well functional. Given the functionality of S-System battery exchange is relatively easy. Unlike in the M4 RIS this time the battery can be stored inside S-System and special wiring is provided with the gun to faciliate this. As in real SIR-system the S-System has holes across its body to allow re-positioning of rail units. Both flip up sights are fully adjustable and the rear sight is secured to low profile position with help of side lever. Similarly front flip up sight has release button to allow positioning to low profile position

Table of Contents:
Real Steel History
First Impressions
Gun First Impressions
Preparing Gun for Firing

Real Steel History:
The M4 Carbine is a family of firearms tracing its lineage back to earlier carbine versions of the M16, all based on the original AR-15 made by ArmaLite. It is a shorter and lighter version of the M16A2 assault rifle, achieving 80% parts commonality with the M16A2. The M4 has selective fire options including semi-automatic and three-round burst (like the M16A2), while the M4A1 has a "full auto" option in place of the three-round burst.
(Taken from

The CAOC and put on a photo contest, which I was lucky enough to win! The Combined Airsoft Operations Command (CAOC) is the first real deal national airsoft organization. They have partnered with great retailers like Airsplat, and put on a photo contest, which I was luck enough to win! The gun was shipped to me soon after, and arrived on my doorstep less than 24 hours after shipping! At the time of writing, the gun is priced at $139.99. It is listed on their site as the "Boyi D-Boys M4 SIR Airsoft Gun AEG Metal." I want to publicly thank for partnering with the CAOC and putting on the contest, as well as providing awesome customer service and great prices! Every order I have had through them has gone perfectly. My service with this gun was great, and I didn't even spend a dime!

First impressions:
The gun arrived in a matte black box with the image of an M4 S-System emblazoned on the front, and the words:


There are a few issues I have with the box info. It makes it sound like it comes with a 12v battery, and 7mm bearing bushings. It does not include those items, it instead has a mini 8.4v battery, and 7mm nylon bushings. Other than that, the info is true. It does come with a high quality three point sling, as well as a metal hop-up chamber set.

Box art

I ripped off the lid and gazed at the work of beauty in front of me!

The box included the gun, one full metal hicap magazine, an 8.4v NiMH small type battery and charger, a very nice three point sling, a nylon foregrip, a cleaning/unjamming rod, and the normal manual. Everything was well arranged in their foam partitions. It's not as nice of a box as their full metal M4SD came in, but it serves its purpose. DBoys is really moving forwards in their packaging.

Gun first impressions:
As I lift the gun from the box, I first notice its weight. When they say full metal, they aren't kidding around. It weighs in at 7.5 lbs with battery and an empty magazine in place. I notice the quality of the paint on the receiver, as well as on the rails, barrel, sights, sling mounts, and magazine. The pistol grip, base for the S-System, and LE style stock are all made of a sturdy feeling nylon polymer. There is a slight wobble in the LE stock, but that can be dealt with later. There is a 1 mm gap between the upper and lower receivers, but it does not wobble. It takes about 15 lbs of pressure to close the gap. You can see a bit of the gearbox through the gap. There is a quality control sticker on the barrel, as well as on the gearbox, visible through the magwell. This is a good sign, since it tells me someone actually looked at the gun and gave a stamp of approval. Let's look at the externals with more detail.

View of receiver gap

Close-up of receiver gap

I am very impressed with the high quality externals on the DBoys M4 S-System. The upper receiver, lower receiver, stock tube, barrel, flip-up sights, magazine release, mock bolt catch and forward assist knob, trigger, selector switch, trigger guard, mock gas tube, bolt cover, charging handle, all RIS rails, both sling mounts, and magazine are all metal. The grip, base for the S-System, and retractable stock are made out of a nylon polymer. There is a slight barrel wobble, which is remedied by tightening the delta ring. The front sight is also a little loose, but is remedied by tightening the allen screws at the bottom of the sight mount. The front sight is a flip-up type, and has the button to lock it in the up and down positions. It unfortunately does not lock in either position, but it sits in both positions firmly. The rear sight is also of the flip-up type, and is spring loaded. It is held in the down position very firmly using a spring loaded clip. When you pull back on the clip, the sight flips up with a satisfying thwack. The sight itself has two apertures, one for 100m, and one for 300m. Obviously, no one will be shooting at these ranges, but it helps with the realism aspect, as well as having a more precise sight picture. The rear sight is adjustable for windage, and has a large, easy to adjust knob. The flip up front sight is adjustable for elevation, but requires two small pin like tools to adjust. You must push down the small spring loaded button with one tool, and rotate the sight tip with the other. Clockwise lowers the sight; counter clockwise raises it.

Flip up sights, front and rear

The S-System consists of a uniform height two piece top rail, two side rails, and a bottom rail. The fixed top half is made of metal, while the removable bottom half is made of a very strong nylon polymer, with metal rails and locking screws installed. It is marked on the bottom with "BOYI SIR-SYSTEM." The side rails have a hole drilled and tapped to accept the front sling mount. The nylon base come off by rotating the flat head screws marked with a lock on the sides behind the rails. You can then slide the bottom forwards, and install the battery.

S-System Base, showing sling mount, and base locking screw (1 of 2)

There are no trademarks on the gun whatsoever. That makes this gun perfect for custom engraving trademarks! The only real steel marking on the gun is "5.56 NATO 17" engraved into the barrel. The gun has a sling mount on the side RIS, and it can be removed and installed on the other side, making it suitable for left and right handed operators. The gun features a ventilated base on the pistol grip, to assist motor cooling. The stock is retractable, and locks into one of 6 positions. It has a slight wobble, but you can remedy this by putting a few layers of electrical tape on the stock tube.

Fire mode markings

Engraved barrel, it looks better in person, it's a hard thing to get a picture of

The S-System RIS can be removed by taking out the three flat head nuts on the side of the top rail, and removing the pins from the other side. You can then slide the whole assembly forwards, and remove it from the gun. The rear sight can also be removed using the same flat head nut/pin maneuver.
Some owners are reporting slight upper receiver wobbles, but I have not encountered any with my gun. This is due to the unique mounting system, which uses the gearbox itself to hold down the upper receiver. The wobble can be fixed by putting some electrical tape on the inside of the upper receiver, where it contacts the gearbox. To accomplish this, take off the S-System base, and unplug the wiring. You can then unscrew the 3mm allen head screw from the front receiver pin, and push out the actual pin. After that, you can slowly slide the upper receiver forwards, taking care to avoid damaging the wiring as you thread it out through the delta ring. After the upper reciever is removed, you can put 2-3 layers of electrical tape on the internal sides of the upper reciever, where the gearbox locks in. Your number of tape layers may vary. As for mine, I have no wobble, so I do not need to perform this at this time.
The pistol grip is made of nylon polymer, with a ventilated metal base plate, and a flat head motor height adjustment screw. The trigger guard is removable, to allow for the installation of different trigger guards.

Another receiver pic

Motor plate

Pistol Grip

Retractable stock

The magazine is metal, and is a Hi-cap type. It feeds well, but fits loosely. It also has a tendency to fall out on its own. It seems like the magwell is too wide for the magazine. This can be remedied by using a flat head tool to pry out the top of the mag catch hole on the magazine a bit. Now, the magazine must be slapped in with some force, but it holds and feeds flawlessly now, with no wobbles. A full wind empties the magazine entirely.
The gun fits and feeds a G&P midcap well. It wobbles, but does not fall out on it's own. It will not fit a JG Hi-cap. It seems like the magazine catch hole is too shallow to securely lock in. These are the only magazines I have currently, but I will be ordering some MAG brand midcaps to test in the next month or so.

Here is the mod to the mag catch

Preparing gun for firing:
To put the battery in, you need to first undo the side screws mentioned above. After sliding the base forwards, place the battery inside, and arrange the wires and the fuse inside so they are not visible when you reinstall the base. Connect the battery to the gun. After you do that, you can carefully slide the foregrip back on, avoiding the battery wires. You can then push and turn the lock screws to secure the base. After loading the Hi-cap magazine with approximately 300 rounds, wind it until it clicks, and click it into the magazine well. Don't be scared to force it in. Just make sure it goes in entirely. Goggles on, weapon on safe, it's off to the range!

The gun has three selections on the safety switch; safe, semi, and full auto. Click it from safe to semi and let out a few shots. Mildly firm trigger pull. I don't have a pull scale, but it isn't overly heavy or light. It is just right. It is quite loud, but does not sound screechy like other MPEGs on the market. Trigger response is very good for an MPEG. Compared to my Galaxy MP5K, JG G36, and JG M16, all on stock batteries, it comes out on top when it comes to trigger response. It seems like it comes with a decent battery stock. A higher output battery would be a good idea, but the gun is skirmishable without it. The ROF is good for an ACM battery, but would obviously be improved by installing a higher quality battery. Short to mid range accuracy is good, but the barrel needs to be cleaned before going too crazy with the gun. The hop-up adjuster can be found by pulling back the mock charging handle. The mock bolt cover will flip down, and you can see the adjustment dial. There is no mock bolt under the cover. This is good, because it makes hopup adjustments easier, but is also bad, because of the decreased realism. Turning the dial clockwise will increase hop; counterclockwise will decrease it. It appears to lock into position well. I don't believe it will walk itself loose with sustained firing.
The gun chronoed at 325-331 with .20 gram Matrix bbs. With regards to accuracy, there is some left/right deviation, but once the hop-up breaks in, I'm sure it will settle in. During my first testing, at 40' I got a 3" wide, 1" tall 10 shot group. Now, I am able to hit man sized targets at 140' 9 out of 10 times after breaking it in a bit. It's not great, but I need to put more rounds through the hopup to break it in, and clean off all remaining oils. The shot groups are improving with every magazine I put through it. A new hop-up rubber may be in order for peak accuracy, but with the stock one in place, its accuracy is acceptable for woodland, and very acceptable for CQB. It is comfortable to hold, as there are no major seam lines on the pistol grip. I recommend installing the included foregrip on the front RIS, to prevent cutting your hand on the rail.

Hop-up adjuster

One of this gun's biggest selling points is the 7mm reinforced type 2 gearbox. The gearbox is bulked up at the rear, near the gears; an area that doesn't receive much stress. Why it is reinforced there, and not near the front of the cylinder, a notorious weak point, is beyond me. The 7mm bushings are nylon, but can be replaced with 7mm metal bushings or bearings. You disassemble the gun like other metal bodied DBoys AR series guns. This included removing the front pin, and sliding the upper receiver forwards until it can be removed. You will need to disconnect the wires from the front, but they include small quick disconnect plugs at the fuse holder to make this easier. The casting on the gearbox looks good, and it has a one piece full metal hop-up unit. The barrel is brass, and is normal M4 length. The gun has a type 0 cylinder, which is unusual for an M4 length gun. I will not be disassembling the gearbox at this time, but I can see that it has nylon bushings, sized 7mm. There are a few reports on the internals of the new DBoys AR guns, and I have no reason to believe this gun will be different from them.

Since the gun is still an AR series gun, there are countless options as far as customization. From new pistol grips to different stocks, the possibilities are endless.
With a plethora of rails on board, you can be sure that almost any accessory you want can be added to the gun. The muzzle is attached to the gun via 14mm- threads, and a small lock allen head screw at the bottom of the flash hider. You can remove it and attach any 14mm- flash hider or mock suppressor, including the TM tracer unit.
With a metal body, you always have the option of custom laser engraving trademarks on the gun, to achieve whatever look you desire. You can remove the S-System entirely, and you are left with a standard flat-top M4 receiver, without a spring loaded delta ring or handguards. This means you can put on other metal body kits, it you so desire. To operate the gun without the S-System, you will need to purchase a free float RIS, or other type of handguard, as well as a device to hold in a battery.

Low price for such high quality
Decent initial FPS
Metal Body
7mm reinforced gearbox
Flip up BUIS
No mock bolt-easier hop-up adjustments
One piece metal hop-up
Blank canvas body
Sturdy build
Easily customizable, due to abundance of aftermarket parts

Some easily fixed wobbles
Front sight does not lock
No mock bolt-less realism
Some reported upper receiver wobble, but is easily fixed
May be too heavy for younger players
A slightly common model

If you are looking for an inexpensive full metal AR series gun, any of the DBoys models will suit your needs. Their bodies are well made, and look great. The good stock performance, great looks, and upgradeability make this gun very appealing for modders, as well as beginning players. There are a few small issues, such as the barrel wobble, and some reported receiver wobbles, but these can all be easily remedied.
I definitely recommend this gun, as well as!

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This airsoft gun is not to be misrepresented as a real firearm or gun that is manufactured by Colt and is merely an airsoft gun that fires 6mm pellets. The manufacturer of this airsoft gun is Boyi/DBoys.



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