Gg Cm18 Inner Barrel

[Shenaf]

I’m wanting to change my inner barrel from the standard 6.05 to a 6.03 in my G&G CM18 Mod1. The current barrel is 375mm. I’m struggling to find a tight bore at 375mm. Is it worth going bigger and adding a mock suppressor to cover the inner barrel. Thinking like a 450mm. Also looking a r hopping as well, possibly looking at changing the hop up to a Maxx unit. Can anyone offer any advice.
Thanks in advance

View attachment 61595

 

[Hudson]

Check out AK2M4. They have a 380mm 6.02 barrel. 

I wouldn't bother getting a longer inner. 

It'll make it less maneuverable for no benefit, and depending on the cylinder it has, might mess up the voluming & ratio. 

 

[Adolf Hamster]

hudson is bang on the money, the ZCI 6.02's are pretty decent barrels and you don't want to be messing with the length too much as any improvement from the barrel will easily be outweighed by poor voluming.

 

[Shenaf]

I will have a look thanks. Would you personally run flat hop or r hop? I am aiming for better groupings as my current set up has proven to be a bit wild. 

 

[Hudson]

What ammo are you using? 

That's your starting point before changing anything inside. 

Buy decent quality, mid-weight ammo and go from there. 

And what kind of performance are you getting currently? 

 

[Adolf Hamster]

again hudson is spot on, hop/barrel upgrades won't do much if you're still firing cheap 0.2's.

for an assault gun around the 0.3g range is a nice balance of price/performance.

flat hops can be cheap and effective, although can be a tad sensitive to adjust. the ml macaron/omega nub combo is pretty good although it can have feeding issues in some guns.

i'd advise against R-hops, when done right they can work well but it's a pain to do the installation and odds are it'll make things worse.

you'll also want to be making sure your air seal is spot on (your symptom for that is vertical dispersion/a wide range of fps readings on the chrono) and that you're keeping the barrel squeaky clean.

 

[Shenaf]

I currently use nuprol either .25 or .28. Depending on weather. The range is ok It’s the accuracy where I am getting the issue I seem to have bbs flying all over. And I have to nearly full hop with .28 to get acceptable range. It chronos at 310 on .20 straight from the box. I’ve heard a lot of bad things about the G&G barrels being made from rubbish metals. I’m fairly new to all this but I don’t want to splash a load of cash on a new gun if I can get this one to keep groupings a little tighter.

 

[Adolf Hamster]

I currently use nuprol

well there's your problem....

And I have to nearly full hop with .28 to get acceptable range.

softer rubber should help, personally i find PDI W-hop or maple leaf macaron in the 50 degree range work quite well.

I’ve heard a lot of bad things about the G&G barrels being made from rubbish metals.

depends on the model, but some of the raiders come with aluminium barrels of pretty shoddy quality, although the ones from brass in their higher end models are decent enough.

I’m fairly new to all this but I don’t want to splash a load of cash on a new gun if I can get this one to keep groupings a little tighter.

shouldn't be too hard.

air seal is a big one on a stock gun, when you chrono you want every shot chrono'ing the same fps each time, if any given shot is over or under by a few fps then it'll mess up your accuracy.

a really good gun will have as low as ±1fps shot-shot

have a look here to see what i mean when i'm talking about air seal, although pay particular attention to the intro because it might not be worth pulling the box apart when you don't have a backup:

 

[Rogerborg]

Spoiled my fun, all I can do is echo all of the above.  The ZCI barrels are decent and longer isn't necessarily better.  And +1 to Maple Leaf rubbers.

If everything goes well you can get results that are too good.  I've just got my project M4 all back together with:

Stock CYMA gears, cylinder and head.

Stock piston head with extra ports drilled into it.

New 19mm x 2.5mm nitrile o-ring, stretched and heated over the cylinder.

Maple Leaf Macaron.60 degree rubber

Omega nub, I think it's a Gear Parts hard, although it might actually be Maple Leaf too.

ZCI rotary hop unit

ZCI 21.4mm o-ring nozzle

ZCI 6.02mm x 229mm barrel

Yes, 229mm, not 329 - this is a chopped down PDW style gun.

Plenty of silicone grease on the o-rings, no PTFE tape.

With an M100 spring I got 374fps. I've had to drop to an M90 to get down to 340fps, and it's consistent to within a couple of fps.

Air seal is everything, and most of the good or bad stuff happens before you reach the barrel.

But once you've sorted that, ZCI barrels are pretty decent. I've linked to @ak2m4 for the parts that I've used, although as with everything in airsoft, your mileage (and fps) is very likely to vary.  This is a works-for-me, not a will-work-for-you.

 

[Shenaf]

Do I need to open the gearbox to change the air nozzle? Can it be done just be prying the tappet plate down? 

 

[Lozart]

Do I need to open the gearbox to change the air nozzle? Can it be done just be prying the tappet plate down? 

No, you'll need to open the gearbox.

Start with the barrel and hope rubber and see what that does. Never change loads at the same time because you won't know what has made the difference.

 

[Rogerborg]

Do I need to open the gearbox to change the air nozzle? Can it be done just be prying the tappet plate down? 

A question we've all asked, hoping the answer will be yes.

But no.  No, that's another dive into the gearbox.  It's always worth double and tripe checking everything before you put it all back together and in the gun.

 

[Shenaf]

Well that’s a shame ?

A question we've all asked, hoping the answer will be yes.

I have ordered a nozzle and shim kit, my thinking being that if I’m there may as well shim the gears.