G&G Combat Machine M4A1 Review

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After having a bit of trouble from my current AEG, I began my quest of finding a low-priced secondary AEG that would be both reliable and durable enough to withstand regular use. I jumped from Dboys to JG to Echo 1, and really didn't like what I saw. I even checked the Classic Army sportline models but was not impressed with what they apparently offered internally. I then happened across the G&G Combat Machine M4A1.

After doing my research, I found the G&G Combat Machine series supposedly uses the same gearbox as their professional GR16 series, though I cannot confirm this. For those that may not be aware, the G&G pro series gearbox includes a reinforced version 2 gearbox, steel gears, G&G HiTorque motor, brass bushings, nylon reinforced piston, metal spring guide, etc. In other words, it's a gearbox you can find in no other AEG within this price range. I have also read through multiple sources and it seems the general consensus is that this gearbox will handle up to an M130 spring with no additional modification, though I cannot comment to the full accuracy of that.

The G&G Combat Machine M4 (now referred to as CM M4) is a highly economical version of the already economical sportline GR16 and can currently be found for around the $140 mark. It features a 1-piece zinc barrel assembly, plastic body, and plastic hop-up unit. Surprisingly, even though this gun is priced with the cheap Chinese clones, it still features a tight bore inner barrel.

First Impressions and Appearance

Opening the box the first thing I noted was that externally, the CM M4A1 is a beauty. I opted to order the Airsoft GI Custom model that comes with a full-metal RIS and a Dboys PEQ2 box which you will notice in the pictures. The standard CM M4A1 comes with the AEG, cleaning rod/unjaming tool, 450 round HiCap, barrel plug, and 1000 G&G .20g BBs. It does not come with a battery or charger.

The body, unlike so many other plastic body M4s, is black. This is an excellent touch compared to the grey bodied TMs, JGs, and E1s. It features a USMC logo in place of the trademark and states that it is a AEG made by Combat Machine in Taiwan. I actually have suspicions that this AEG is a rebranded "Combat Machine" brand AEG that G&G threw their gearbox, motor, and hop-up into. Why? No where on the box nor on the externals of the gun does it mention G&G aside from the retractable stock. Either way the gun looks great and the fact that the body is plastic isn't evident until you pick the AEG up to truly examine it. The charging handle (which is a tad bit flimsy) and forward assist work, but have no function. The dust cover stays tightly closed yet is easily opened with a pry of a finger which exposes the front of the gearbox and the hop up unit.

Feel & Build

The gun is actually very solid for a plastic-bodied AEG. Apparently the body is some form of nylon/plastic combination that is supposed to withstand the brutality of a hard-day's play. Since I'm not about to bang the thing up against a rock, I can only say that the body definitely isn't the hard grey ABS plastic body many other AEGs have; this material seems similar to what G36 bodies are fabricated from. The AEG has no barrel wobble like the Tokyo Marui series M4s were notorious for. This truly amazed me, especially considering my model has a metal RIS combined with a plastic body. It does, however, suffer from a bit of barrel tilt. If you torque the barrel left or right like you're screwing it on it tilts, maybe, 1/16th of an inch. Note that this is almost unnoticeable and because it tilts on an axis, it will never affect accuracy. The gun is fairly light as expected with the plastic body, but it still has an extremely solid feel. You can hold it by only the pistol grip all day if you wanted. There are no receiver gaps, loose stocks, rattles, or wobbly barrels that other models may have. In terms of build quality, this is a top-notch plastic-bodied M4. Trust me, I've held many that were not.

Metal content includes: Barrel, front sight, d-ring, mag release, bolt catch, selector switch, trigger guard, buffer tube, charging handle, dust cover, and rear sight. Please note that the gun does not come with a metal flash hider or carry handle. It also appears to me that the barrel and entire front sight are one unit that are cast together.

Performance

With the hop-up adjusted properly and the noted tight-bore inner barrel, the CM M4 ranges just below my AE MP4A4 with an M110 spring (within about 10-15ft). The added barrel length and tight bore make up for the FPS difference between these two. The effective accurate range with .20s is easily 100-120ft. You can hit targets past that in excess of 150+ ft although it won't be excessively accurate. The gun fires with a very crisp sound; it's neither a harsh "WHACK" nor a wimpy grind like some guns have. It's very satisfying to shoot. With an 8.4v 1500mAH battery, the ROF is reasonable though not extreme. If you're looking to get a great ROF from this gun, I highly recommend an 9.6v, especially if you intend to further upgrade it internally. The reinforced gearbox is a bit much on an 8.4v mini battery, though it is manageable. Statistics say the gun fires around the 330fps range, though I expect it to be a bit higher than that. Either way, then gun is a great performer in relation to guns of even a higher class.

 Disassembly & Internals

The CM M4 practically disassembles the opposite of the ICS series of M4s. In order to break apart the receivers, you simply tap out the front body pin just behind the delta ring and pull the lower receiver parallel away from the upper receiver. Doing this gives you access to the hop-up, inner barrel, and the upper part of the gearbox (which you can't do much with). Further disassembly to remove the gearbox involves removal of the motor, rear body pin, mag release, etc.

Unfortunately for this review, I'm not going to comment on the internals. Why? For 1, I'm not going to go inside the gearbox until I get a new M110 spring to install and 2, there are many resources on the internet that have done this previously so I feel it is not immediately needed. I will say, however, that the cylinder of the G&G gearbox is a metallic blue as opposed to the brass-colored ones I'm used to seeing. Note, too, that when I install the new spring in this gun sometime in the future I will be sure to update this portion of the review.

Summary

Overall, I must say this this gun is well worth the money and is leaps and bounds above similarly priced competition especially in terms of internal reliability. The tight-bore barrel, G&G gearbox, and durable body more than makes up for the fact that it does not come with a battery or charger. To be honest, I would recommend this OVER a Tokyo Marui series M4 any day of the week. It's a beautiful, durable, and efficient AEG that can easily take the role of a first/primary AEG or secondary/backup AEG. You really cannot go wrong with this gun.

So, the pros and cons in closing:

PROS:
-Build Quality and appearance
-No notorious barrel wobble
-Excellent gearbox and internals
-Tight bore inner barrel
-Easily adjustable hop-up
-Versatility in terms of accessories
-Moveable charging handle and forward assist
-450 Round HiCap

CONS:
-Slight barrel tilt issue
-Wiring appears to be of a very small gauge
-Plastic body (although durable)
-No metal flash hider included
-No battery/charger included
-Moderate rate of fire on an 8.4v mini battery

INTERNALS

This weekend I finally got the chance to look at the internals of the G&G CM M4A1. A friend needed an SP110 installed in his so I took the opportunity to get plenty of pictures for review purposes.

First off, disassembly is quite complicated for a first-timer like myself. Using the GR16 disassembly guide on YouTube, I was able to have the gun disassembled and the gearbox out in roughly 30 minutes. The trigger body pin gave me the most trouble, but now that I know how everything works, I would estimate disassembly time to be around 15 minutes or so.

Now on to the internals. Upon first glimpse it is seen that the gearbox features copper bushings and what I have now found to be a polycarb selector plate unlike many other guns within this price range; most others have plastic bushings. Also the gearbox and the selector plate denote the GR16 proline "trades". Notice anything unusual?

The gearbox screws are on the left side as opposed to the right.


Inside: Excellently made steel gears, metal spring guide, some weird blue cylinder, a very strong and beefy tappet plate and spring, and what appears to be a polycarb piston, though I cannot confirm this. The bevel gear has 6 anti-reversal notches... something that not even my AE MP5 has. Also the stock spring is a progressive-rate style spring... what I would guess to be an SP100. This gearbox alone is actually very nice for the money. No JG or Classic Army sportline has internals up to par here. Do note, though, that THIS IS NOT THE SAME GEARBOX AS THE PROLINE. The cylinder head, cylinder, and spring guide appear to be the main (possibly the only) differences.

The piston, piston head, and cylinder all look to be fine. I'm not sure about the blue cylinder; it's something I'd never seen before. The piston is very nicely designed with the second to last tooth already removed, and the "first" tooth is metal. Also the piston head is the unique G&G style piston head with the teardrop ports. Spring guide is of beefy metal, but it is not a bearing spring guide.

Piston & Spring Guide

Cylinder & Head:

 Piston Head:

I need to say that I was very surprised to discover one thing... the gun had literally NO, NONE, ZILCH compression! By covering the cylinder nozzle and shoving the piston into the cylinder it would freely glide all the way to the end. An assembly with good compression is nearly impossible to do this with. I swapped the stock o-ring for a #14 O-ring and the compression was stellar. Very, very good seal with the new ring.


Additionally, though not in the gearbox, this is the motor. I cannot say much about it as I don't know a lot about motors but it is a beefy one and is a TAD bit sluggish in an 8.4v. On my friend's 9.6v this thing screams, though.

So... popped the new spring in, assembled everything, and the gun worked fine. Overall, I still highly recommend this over any other gun within its price range including CA Sportline, JG, Echo 1, AND Yes... Tokyo Marui. You just cannot get such a solid gearbox from anything in this range.

As for my rating... I give it an 7.5/10 given the lack of compression and I'm still unsure about the piston material even though it is very well designed. Maybe someone could give me a definite as to whether or not it appears to be a polycarb.

For upgrades to anyone interested I would only really suggest replacing the spring guide with a bearing spring guide, and replace the stock o-ring. The stock spring is slightly weak so anything around an M110 or above would do fine in this box without running the risk of imminent failure. Keep in mind that none of this is necessary... just preference from research I've done.

Have any questions or comments on this review? Ask in the forums!

http://www.airsoftcore.com/forum/index.php?showtopic=50667

doink - February 7, 2010 The O ring is a very unusual very strtchy rubber and the faster the piston head moves the wider it gets so it seams like it has crap compression at first but it actually has awesome compression standard. You can try, the the faster you move the pistion in by hand the tougher it gets. G&G a

Recon72 - February 11, 2010 Would I have to upgrade any internals if I put in a G&G M120 spring? Thanks.

Recon72 - February 11, 2010 Also... Would I have to upgrade the internals if I put a G&G M130 spring in? Thanks.

Slap - June 25, 2010 Looks a type 2 cylinder. If you swap it out for a type 1, your gun will shoot much better. I am assuming from the picture of the gun that the barrel is 363mm

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