G&G Combat Machine M4-A1 (M16 Carbine) Review

By: hydralover 1/09



This is the newest release by G&G in their line of Sportline Models. G&G Sportlines are relatively new on the airsoft market, and supply a new choice to those of us looking to buy a decent replica for under 200 dollars. The G&G Sportlines have been hailed as the best choice of a cheap, reliable AEG, so in this review, we’ll see whether it lives up to its name. If you have any suggestions, questions, comments, or corrections, feel free to post up or PM me.

Specs:

$140 at AirsoftGI (The other sportlines models cost around $170)
~335 FPS
19 RPS with an Intellect 9.6v 1200mAh mini battery, measured with Audacity and checked enough times to be certain.

Description:
The box that the AEG comes in is…very flashy, as you can see for yourself.



In the box, it’s very plain. Just the gun, hi-cap mag, and cleaning rod. Sadly, the padding is terrible. The gun is held in place by a very weak plastic molding. At least the JG AUG I reviewed had foam…



To test the strength of the packaging, I put in its side, and gently pressed down. You can see where the plastic bends (near the front sight). Weak.



The Combat Machine chronoed in at 335 FPS, at AirsoftGI.



Taking the gun out of the box, I was surprised by how light it was. It felt like I could carry it around all day without a problem. I could easily swing the gun around because the gun was light and maneuverable. It felt like a toy at 5.6 pounds. Then again, I’m used to carrying around my CA CQB SEAL, which weighs in at 7.2 pounds. The Combat Machine Carbine still felt solid enough, and pleasant to hold.

The hi-cap that came with the Combat Machine is longer than standard m4 hi-caps. Here is a comparison shot between my Airsoft Elite hi-cap and the G&G hi-cap.



The G&G hi-cap is a darker shade of grey, and holds around 400 rounds. On the bottom, there are some G&G Armament trademarks stamped. Unfortunately, there is no key wind ability with the G&G hi-cap.



Externals:
I will be reviewing the Combat Machine M4 Carbine from the muzzle to the stock.

The flash-hider comes with a dark red cover. The flash-hider itself is completely orange, and surprisingly, is made of a very hard plastic. I can’t be sure, but it seems like the same material as the receiver: a hard fiber. I had a hunch that the material itself was orange, not just paint. To test this, I cut a small piece of the flash-hider itself, and indeed, the flash-hider is made of orange plastic. No paint remover on this one.



What’s interesting is that there is no set screw in the flash-hider, so I’m assuming that it has been glued on. To remove it, you could heat it up by dipping the tip in hot water, or I’ve heard that blow-dryers work. I won’t actually take off the flash-hider (it’s not my personal gun, I bought it for a friend, and will be returning it to him as soon as I am done with my review, so I won’t risk damaging it), but since some of the threading can be seen inside the flash-hider, it can be concluded that the threading is 14mm CCW.
The outer barrel and front sight assembly is made completely of metal, and looks just like any other m4 model. The metal is slightly shiny, though, especially compared to my CA CQB SEAL. The front sight is non-adjustable. The front sling mount swings loosely, but is sturdy enough (I gave the gun a few good shakes holding it by the mount).



The handguards are built well, with just a tiny bit of wobble. There are, however, cracks between the two pieces that can be seen.



This post has been edited by hydralover: Jan 8 2009, 11:21 PM

To take off the handguards, pull down (towards the stock) on the delta ring behind the handguards, and the two pieces will be able to be pulled off. The spring behind the delta ring is quite stiff, and sometimes makes it difficult to put the handguards back together. Sometimes I get it on the first try, and other times I have to struggle for a minute or so before the handguard goes back in place. There is no way the delta ring would come loose unintentionally.



The fuse and wiring, as well as the mini battery connectors, are revealed. In the handguard, the largest battery you can fit would be a 9.6v nunchuck (AA cells). Mini 9.6v and 9.6v nuchucks (2/3A) will fit without any problems.

The carry handle is mostly plastic (the same nylon fiber that the receiver is made of), with the exception of the knobs, bar, sights, and adjustment knobs, with two settings just like any other clone. There is a hole in the top for attaching a carry handle mount. The only special thing is that there is a “G&G” logo on the left side, next to the sight.





On the right side, on the adjustment knob, there is an “R” with an arrow. Quite different from my CA, which has numbers marking the different positions, as well as an “L” with an arrow.



The carry handle can be removed by unscrewing the two knobs, then simply pulling off the piece. Underneath, there is a nice, metal 20mm rail for mounting optics and other accessories.



The G&G Combat Machine M16 Carbine is the first in the series to have actual trademarks, instead of G&G’s usual markings.

Trademarks on other Sportlines (picture courtesy of AirsoftGI):


USMC Trademarks on Combat Machine:


Blank right side of receiver:


A thing I noticed about the Combat Machine’s trademarks is that they are painted on, and on top of strange boxes… I’m not quite sure how to explain it. The receiver has these two boxes that the trademarks are painted on. You can see them in this picture. There is a similar box covered by the middle trademarks as well.



The trademarks aren’t the most durable thing in the world (I could easily take off a bit of the paint with just my fingernail and a little force), so I would be careful with them. They do look nice though, in my opinion.

This post has been edited by hydralover: Jan 8 2009, 10:48 PM

The nylon fiber body is quite nice. It doesn’t look like the other plastic models, it’s a darker flat black, and feels nice to the touch. It’s very sturdy, and doesn’t feel like it’s going to break anytime soon. I could tell people it’s a metal body, and they would believe me as long as they didn’t closely examine it.

The mag catch is your standard mag catch, nothing special. There is a problem with it, however. More on this part later.

The forward assist is pushable, but does nothing.

The charging handle pulls back and clanks forward, nothing special. However, it is worthy to note that it doesn’t open the dust cover.



The dust cover is quite different from the one on my CA. It is spring loaded, but the spring pushes the dust cover CLOSED, instead of open. The spring can easily be seen from the outside, which slightly detracts from the appearance. There is no magnet holding the dust cover closed. This is quite a hassle, because you can’t adjust hop-up easily. You have to pry and hold open the dust cover each time you want to change your hop-up setting. What makes this harder is that there is no notch in the middle like on CA models, you must open it by sticking something (usually your fingernail) under the dust cover and pry it open that way. Something worth mentioning is that the dust cover doesn’t really fit in the space it’s supposed to, and can move around in its notch. This might have been on purpose, but it’s slightly smaller than the area it is in. However, this lets us more easily open it.



When the dust cover is pulled back, you can see that there is no mock bolt. The gearbox is exposed, as well as the hop-up assembly. Like other m4 models, there is an arrow guiding you in the right direction whether you want to increase or decrease hop-up (turning the wheel clockwise increases hop-up). The hop-up is EXTREMELY difficult to adjust.



I’m not sure which is right, but the Combat Machine’s externals are different from that of CA. On the CA, the shell casing deflector smoothly connects with the receiver. However, on the G&G, it appears to be cut. A picture is worth a thousand words, right?

G&G Sportline

Classic Army

This doesn’t really affect anything, but since I’m trying to be thorough, I mentioned it. Some hardcore realists might find use for this piece of information, though.

Now on to the selector switch. This is my main complaint about the externals of the G&G Combat Machine. The selector switch is loud and clacky, and doesn’t have much feedback when switching firing modes. I much rather prefer the selector switch on my CA. The G&G just feels flimsy.



The grip looks like any other m4 grip. It’s the same material as the body, which is okay, but not great. It’s definitely not as nice to hold as my CA, which is made of tackier material. The grip plate is made of nice quality metal, though.

Near the trigger, there are very ugly molding lines where the two pieces of the lower receiver were attached during assembly. The lines are clearly seen, and not quite clean.



The buffer tube is made out of the same shiny metal as on the rest of the gun, and is solid. The plastic stock, however, is wobbly, and the adjustment piece has A LOT of play. It feels really weak. The stock clicks nicely enough into place, even though it slides much too easily for my liking. The rear sling mount is sturdy.



Performance

Unexpected Problem:
When I took the AEG to a game, its performance disappointed me. The first problem I noticed was that the Combat Machine is VERY picky with magazines. Neither my Airsoft Elite hi-cap nor the stock G&G hi-cap that came with the gun fit well into the magwell. What would happen is that the magazines would go in halfway, but wouldn’t click into place. It required a large amount of force and some wiggling to get the magazine to sit properly in the magwell. The mag doesn’t go in or out smoothly, and the mag catch sticks a lot of the time, making the mag release unreliable.
Also, on full auto, the mags would feed around 3 BBs, then stop feeding at all. I tried a friend’s midcap, and it fed fine. Since the hi-caps work (and fit) fine in my CA as well as my other friend’s Echo 1 m4, and a p90 first factory box mag, it would be safe to say that the problem is not the mags. Rather, the G&G Combat Machine has some feeding issues with some magazines, including the one that came with the AEG. This problem renders full auto practically useless, and forced me to use semi-only during the games I played with the AEG.

Accuracy and other Issues:
The accuracy on the Sportline was sadly lacking. With the hop-up tuned, the BBs reached about 80 feet before dropping. I used TSD Tactical .25g BBs. I was outranged by my friend, who was using a stock Dboys RK-01 (AKS 74).
Using a 9.6v 1200mAh mini intellect battery, the trigger response was satisfying. The gearbox doesn’t have much whine, and operates smoothly.


Coming up: Accuracy tests in controlled environments, and disassembly!

This post has been edited by hydralover: Jan 6 2009, 11:10 PM

Great review! I'm surprised at how poorly made it is though. Sounds like it could be much better. Do you think it would be good to get this over a JG M4? Or a TSD sportline M4?

Well, it's not poorly made at all. I only have a few major complaints: the selector switch, which still functions perfectly fine, and the mag catch/mag feeding issues, which are much more serious problems. The rest of the problems aren't really noticeable in a skirmish.

I don't have any experience with the TSD Sportlines.

I would get a JG m4 over this, but ONLY because of the mag issues. If this was a lemon, and it's proven that the other G&G Combat Machines Carbines don't have feeding issues, I would DEFINITELY get this over a JG. The build quality both externally and internally is just so much higher.

This post has been edited by hydralover: Jan 6 2009, 11:16 PM

nice review. I have the regular sportline and from your review the only differences I can see are the quality of the finish on the metal, the blue cylinder since mine is gold, and the hop up unit looks different, and of course the trademark. I think G&G might have made a sportline with different internals than the regular sportline and the prolines cause of the differences of the hop up unit and cylinder color. The accuracy on my regular sportline is great. I can easily hit out to around 170 with hop up adjusted(no joke). I think G&G wanted to make a even more affordable sporltine in this one to compete the the prices of the classic army and the tsd sportlines. I also think that your dust cover spring was put in backwards cause on my sportline it opens the dust cover and you have to push it close because of the spring and I have never heard of you having to pry it open and if the charging handle moves it should open the dust cover

BTW
my selector switch clicks and is pretty stiff

This post has been edited by sergantsnipes: Jan 6 2009, 11:09 PM

I meant as far as performance goes. Sounds like it's not nearly as good in performance as the G&G sportline series.

Well, the dust cover spring was turned around the dust cover, so I'm pretty sure it's not put in backwards (hard to explain and hard to take a picture of, but trust me on this one).

Charging handles don't always pop the dust cover. On CAs, charging handles don't do anything. There is a magnet that holds the dust cover in place.

The selector switch clicks...but is really loose.



I wouldn't know...I haven't had any experience with the other Sportlines.

I'm going to be doing some more accuracy tests to see if maybe it was just an off couple rounds for me, or bad BBs, or bad wind conditions, or mental freak-outs because I was on semi only, and such. I was playing fine with my CA CQB SEAL, though.

This post has been edited by hydralover: Jan 6 2009, 11:26 PM

Good review. Thanks for posting it. I think I'll skip the Combat Machine and go for the Sportline or the full metal (if I can afford it).

^I second that.

Hmmmmmm...kinda disappointing. The externals sound fine for me but it's the internals and accuracy that gets me, 80 feet is pretty bad, I could almost throw a bb that far jk lol. But to make it cheaper obviously they have to make the cut somewhere.

This post has been edited by SoLDieRBoY: Jan 6 2009, 11:46 PM

Like I said, it could have just been that day, those BBs, or me. I'll iron out the accuracy tomorrow morning (when it's daytime).

The internals are fine except the mag issues. It shoots smoothly.

Interesting. A bit different from my experience. While looking at your seventh picture, I noticed you had a chip in the flash hider. Funny, because mine actually came this way. The barrel plug was off of the gun, with the same size chip in the same exact place on mine. Oh well, doesn't bother me. I also had to agree with the padding of the gun. That thin plastic is just obnoxious.

I do agree on the dust cover. I had to use scissors to pry it open. Not really a big deal for me though, because I tune the hop up once (just making it hop up a little bit) and I leave it. I will probably never touch the dust cover again.

One thing that is different is the selector switch. It was an average switch to me. No problems whatsoever. A smooth action, and a very nice and solid click right into place.

Another thing I agreed with was the magazine issue. The stock hicap has a good amount of wobble.

The last part was the part that stuck out the most. I had absolutely NO issues while shooting this. The hicap was perfect, even though I don't use them. Every bb fed, and it was easy enough to get the mag in. Just pop it in and "click". Full auto was perfect for me. I was shooting at about a 8" x 8" square metal target. I shot a burst of about six, and I counted two bb's that missed. While shooting it on semi, about one half of the bb's would hit. This is also using unadjusted iron sights and the little bag of bb's that came with the gun. There was also wind.

It's unfortunate to read about the shooting experience with your CM, because overall, mine was excellent. The hicap is good enough for me while I get more midcaps.

Great review, hydralover.

The flash-hider did come like that. The part I cut out isn't noticeable.

I cut my fingernails, and now have a hard time opening the dust cover. It's really quite annoying.

Hm. maybe I got a lemon or something...something weird with the body.

I did a quick accuracy test just now (it's nighttime, so I can't really see where my BBs are going...so I'll do more tests tomorrow morning). From 80 feet, shooting prone (supported by many blankets, more steady than you'll likely be shooting in a game) the spread was 8 inches. Again, this was just a really quick test.

Nice review Hydralover! Approved...

I made a quick video describing the mag issue.

http://www.youtube.com/watch?v=2cheyxvMSXE

I too just got this gun delivered today and fired a few shots about 80 feet also, was able to hit the target most of the time, but the wind still knocked some of the bb's off course. As far as the magazine issue, I haven't had any trouble with it at all. Slides in smooth and comes out easy, though there is wobble when its in the gun.

I did some accuracy tests 20 minutes ago. Here are the results, shooting from 80 feet in a prone position, propped up by blankets. Please keep in mind that the grouping sizes I wrote on the paper are not definitive, as some of the BBs failed to hit the paper.











For disassembly and internals, scroll down or click here: http://www.airsoftforum.com/board/index.ph...&p=17935736

This post has been edited by hydralover: Jan 6 2010, 06:10 AM

Interesting results, hydralover. I'll have to do the same thing and post up a pic. I'll probably just edit this post later today.

More news, guys. When doing the accuracy tests, I decided to fire full auto to finish off the hi-cap after I finished. The mag started feeding more than 3 BBs! However, there were mis-feeds and double-feeds all the time. I'll lube up the gun while I take it apart, and shoot off another hi-cap later on today. See how that goes.

Once again, the G&G hi-cap feeds perfectly fine in my CA CQB SEAL, which is shooting faster (higher ROF) than the G&G Combat Machine.

I also noticed that the trigger pull on the G&G Combat Machine sometimes seems to get ALOT shorter...Maybe the trigger block is malfunctioning somehow.

This post has been edited by hydralover: Jan 8 2009, 04:43 PM

Great review!
I think this would confirm that at least some internals (blue cylinder) on the Combat Machine are not the same as the normal Sportline Gr-16.

I did more shooting with it today too, I seem to be getting ALOT of misfeeds now, not sure if its the mag thats the issue as im not to knowledgeable on these guns yet but when I go full auto it fires 2 or 3 bb's then nothing, remove the mag retry same issue. Do any of you think getting different mags would solve this issue?

To me, saving $30 doesn't compensate for that.

Well hydralover already said that he had misfeeds with the other one. I'll try JG, MAG, and STAR mags in mine. I don't think wobble will go away, but hopefully some good brand mags will cut down on the issue.

I actually figured out the problem. I'm done with taking apart the gun (just need to write it up and upload 40 pictures or so), but when putting it back together, I first put the gun together without the hop-up. The mag fit fine. No problems inserting or taking it out. But then when I stuck in the hop-up, the old problem came back. So the hop-up has some compatibility issues. A new hop-up chamber should fix this.

LTech, that's exactly what I'm talking about. I would take a video of it, but there's no way the camera could catch the BBs flying out of the barrel.

I know that I tried a midcap that worked fine. That's it, though...no other experience. StarvinMarvin, if you can see if MAG mags will work, that would be great.

Disassembly

Ahh my favorite parts of doing a review…taking apart the gun.

To disassemble the G&G Combat Machine Carbine, simply follow the directions for any front-wired, tab-less carbine. I did notice a lot of things that are different while taking apart the gun, however.

First of all, the forward body pin has a kind of slit in the middle, which fits in with a bump in the lower receiver’s edge. It’s hard to explain, but basically, you can’t remove the front pin. I have no idea why G&G did this, it doesn’t seem to have any purpose except to get in the way.



To take off the upper receiver, punch out the front pin as much as you can, then slide the upper receiver forward, but not all the way!. Be careful with the wiring; it won’t let you separate the upper and lower receivers at first. I cut the ziptie holding the wires to the outer barrel just to make things easier. The charging handle will catch on the gearbox, simply push it up and over anything in its path. If you have problems with this part, pull the charging handle. Between pulling the handle and pushing it over any obstacles, the upper receiver should slide forward pretty easily. Once you’ve pushed it about halfway down the gearbox, until the wiring gets in the way, then simply flip it up and over the sides of the gearbox. Don’t worry, it won’t break.

Here’s a picture of the plastic one-piece hop-up chamber and the lightweight inner barrel (supposedly zinc). The hop-up chamber says “G&G GR-16” on the left side.







Here’s a picture of what you should have now (I punched out the rear body pin before taking this picture).



Now punch out the rear body pin. I noticed that this pin seems to have an o-ring… No idea why, because there would be no reason for compression in between the body and the gearbox around this area.



Take off the LE stock by pulling DOWN on the adjustment knob. Then look at the bottom of the buffer tube, and locate the Phillips screw. Unscrew it, then pull out the buffer tube cap. This was slightly difficult to remove; I ended up getting a flat-head screwdriver and prying it open. The cap on the Combat Machine is HUGE compared to other models I have disassembled. I don’t know why they did this, again, there doesn’t seem to be a reason for it.





Get a long screwdriver and remove the screw inside the buffer tube. The buffer tube is quite snug against the back of the lower receiver. Also, there is only a small hole inside for the screw to go through.





This post has been edited by hydralover: Jan 8 2009, 10:49 PM

In my CA CQB SEAL, there is a removable metal piece that holds the screw in place in the buffer tube. However, on the Combat Machine, the guide hole is not removable. This means that you can’t put any wires through the buffer tube. If you want a crane stock or full stock without exposed wiring, you need to get a new buffer tube. I don’t know why they didn’t just have a metal piece to guide the screw…

Next step is to remove the motor. Unscrew the two screws holding the grip plate, and then remove the plate entirely. There is no thin washer! I consider this an improvement over other models, as it is much easier to disassemble/reassemble the motor area, and it still does its job.



Carefully disconnect the motor connectors, and pull out the motor. The motor connectors are firmly connected with the motor tabs, and the wiring all looks very well done. The motor itself is non-descript, and has no markings.





The motor seems to need a lot of juice to run. It blows right through my intellect 9.6v 1200mah batteries. During testing, I went through 3 cycles of batteries.

Next, unscrew the two screws inside the grip. Then carefully remove the grip from the gearbox, taking note of the wiring. Be careful when putting the wires through the holes in the grip.

Now you have to remove the mag catch. This is quite different from other models. On every other carbine model, there is a screw to undo on the tip of the mag catch (on the side where you press in the button to release a mag). However, on the Combat Machine, there is no screw! The button is simply screwed into the L-shaped piece. After a couple minutes of examining the mag catch, I found a way to remove it. Push in the button, HOLD IT THERE, and then unscrew the mag catch from the OPPOSITE side (the side with the long bar). The body should hold the button in place when it is pushed in, and you can unscrew the two pieces by rotating the long bar. When you are done, you can remove the L-piece, then relieve pressure on the button. Be careful, as the button is spring-loaded, and the spring might fly out, never to be seen again. This design is pretty dumb in my opinion, as it requires a lot of extra work.



Remove the trigger pin. Push from the right side, punching out the pin to the left. You can actually see which side of the trigger pin is rugged and which is smooth, so don’t try to punch it out the wrong way (you won’t succeed, and you might damage something).



Finally, wiggle the gearbox loose. I like to start at the rear, where the top of the back of the gearbox sits in the lower receiver. Switch the selector switch to semi, and pull the back of the gearbox up and out of the lower receiver. This shouldn’t be that much of a problem, but if it is, don’t be afraid to use some force.

And here’s your gearbox!




Coming up as soon as I finish uploading more pictures: Internals

This post has been edited by hydralover: Jan 8 2009, 11:24 PM

Internals

I’m going to be diving in to the gearbox in this section of the review.

The first thing I noticed is that…the screws are on the wrong side of the gearbox!?!? This confused me, because I can’t think of what benefits could come out of having the screws on the left side of the gearbox… You still need to open the gearbox with the cylinder facing right (well you don’t NEED to, but it’s highly advised that you do), because of the tappet plate being attached to the left side of the gearbox. Also, all the gears would be upside down if you tried to open it upside-down. So basically, the design is making you unscrew on one side, and then flip it over to crack apart the two shells. No idea why they would design it like that, but okay…

Also, there is only one motor screw…



Here’s a picture of the internals of the gearbox after I separated the two shells.



The spring guide is a hefty metal, and has no ball bearings. Pretty well made.



The spring has irregular pitch. A pleasant surprise was that it wasn’t attached to a metal piece inside the piston, which means that the piston head screws in from inside the piston. The spring is free inside the piston, making spring swapping a MUCH easier task.



The piston is made of a grey polycarb, and is nicely built. What immediately caught my eye is that the 2nd tooth is already shaved off! This saves us the trouble of dremeling off the second tooth to avoid pre-engagement. Very nice.



The piston head is the same grey material, and has 6 ports. These ports are slanted, which supposedly helps air flow out to the o-ring. As mentioned before, it screws in from inside the piston.



The tappet plate was very well made. Strong polycarb, felt as durable as a Guarder tappet plate. Air nozzle was okay, nothing special.



The cylinder is very lightweight, and made out of a blue material. The cylinder head is poorly made…a white, cheapy-looking material. Looks like a cylinder head out of an A&K gearbox.



The air compression was TERRIBLE! There was absolutely NO compression. I could not, no matter how fast I pushed the piston is, create any air flow. Blocking the air nozzle with my finger, the piston slipped into the cylinder just as easily as it does without my finger. Even the JGs I’ve disassembled had better compression than this… this was just sad.

The grease job was mediocre. There was some weird yellow grease on the bushings, though…

The 7mm solid bushings are made out of brass, I believe. The gears look nice, made of a nice quality steel. The anti-reversal latch was HUGE and beefy. It’s actually one solid piece of metal, instead of a 2-piece latch I’ve seen on most other guns. Well done.

The sector gear is well made, but the tappet plate nub is a separate piece. This was interesting…I don’t know why they didn’t just make it one solid hunk of metal. I guess it doesn’t really matter that much.



The spur gear has “G&G” stamped on it, which might be of interest to some of you. The bevel gear is well made, too.



I tested the shimming on the gun by screwing in 5 screws around the gears, and then poking the gear axles to see if there was any play. Turns out, the shim job was very loose… All 3 gears had play; the sector gear had a bit less than the others. Using my past shimming experience as a guide, I would say the sector gear’s play was .3mm, and the spur and bevel gears both had .5mm of play.

The trigger assembly looked good. Nice solder jobs, and a beefy trigger post. Doesn’t look like it’s going to break anytime soon. Something strange I’ve noticed about the trigger… When the battery is low, it seems like the trigger pull is A LOT less. I don’t know why, I don’t know how, but I know that it happens.



Here’s a picture of the gearbox being reassembled.


The gearbox shells are made out of a very nice material. They look nice, feel nice, and sound nice. I would trust these shells with reasonable setups. On the outside on the left side, “G&G Armament” is stamped on the shell.



“GR-16” is stamped on the selector plate, which is also made out of a black polycarb and seems durable enough.



Final shot of the gearbox:


While putting the gun back together, I thought I would experiment with the hop-up and magwell, as I have had some problems in these areas (see above posts). First, I put the gun together without the hop-up/barrel assembly, and then tested the G&G hi-cap that came with the gun. To my surprise, the hi-cap fit perfectly. The mag catch worked properly, and there were no problems. Then I tried re-installing the hop-up, and the problems came back. So I would say that the hop-up has some compatibility issues (maybe its dimensions aren’t right, and are slightly too big, pushing the mag down in the magwell just enough to affect the mag catch). A replacement hop-up should fix this. Maybe later, I will swap out the hop-up assembly in my CA for the one in the G&G, and see what results come up.

So after putting the gun back together, I test-fired, and to my pleasure, it cycled just as nicely as it did before I took it apart. Well made gearbox by G&G. The gun is definitely worth the $140.

I just spent an hour trying to figure out why the gun has been having mag issues. I found out that it's not the hop-up chamber that's faulty. I replaced the chamber with my CA hop-up, and the gun was still having the same mag issues. Then as a second trial, I tried inserting the mag just by itself (no hop-up), and it fit fine. This leads me to think that there is some measurement issue with the body of the G&G Combat Machine, which pushes the hop-up chamber out of place just a tiny bit, which in turn leads to magazine issues.

Hmm, you mentioned you also tried a midcap mag that worked with no issue, what brand was that?

I can't remember. I've racked my memory, but I never asked the guy what brand it was...

It was a VN mag, that's all I know.

Updated list using Hydralover's dissasembly pics

Different from Sportline/Full Metal Gr-16:
Cylinder
Cylinder head
Inner Barrel
Piston (not entirely sure though)
Stock tube
Body (different trades, but appears to be built the same way)

And just for comparison, I have never noticed feeding issues with my standard Gr-16.

Thank you for that, I know that alot of people are wondering what's different between the two. If possible, could you upload pictures of your regular Sportline's internals?

Update on the mags: I lubed up the hop-up chamber and mag catch. The mag catch sticks less now, but still does every so often. The magazine fits better in the magwell; the problem I explained earlier happens less often now. Instead, the mag gets stopped just short of clicking into place. If I slap the mag after each time I insert it, it reliably catches correctly.

After lubing the hop-up and magwell, there were still misfires and double-feeds galore.

This post has been edited by hydralover: Jan 9 2009, 07:51 PM

I figured out my problem too, my hicap mag seems to be defective or something. I tried my friends G&G Hicap and it seems to have fed correctly. No misfires & correctly fed, although it was still wobbly inside the gun. So for now I just ordered another hicap to replace the one that came with the gun.

That's strange. Neither my G&G hi-cap nor my Airsoft Elite hi-cap work properly...

Sure, I'll see if I can get them up this weekend.

It could have just been hop-up being not broken-in(you did not tear apart the gun and wash the hop-up bucking, right?)

Hop-up does not need to be broken in.

There are always grease on hop-up buckings when the guns come out of the factory.

Is there any chance that the barrel is made of aluminum?

Quite possible...when I first took a look at it, I thought it was aluminum. It certainly felt like it. But then I did a little research online, and all the sources pointed to zinc...