Upgrading Gg Cm16 Combat Machine Mod 0- Need Help

[bluyeti]

Hi Guys,

I was wondering if you could help me upgrade my gun.

 

I am currently running a G&G CM16 Combat machine, that shoots around 320fps. 

- I have already flat hopped the gun and replaced the bucking.

 

I am thinking of upgrading the spring, which one should i buy and will the rest of the stock internals hold up- or will they need to be replaced too?

 

Thanks :)

[RonLancs]

Hi mate, 

 

When you want to upgrade first you have to ask yourself what do you want out of it. Upgrading the spring will either increase / decrease the FPS - this doesn’t directly make a difference in accuracy or range. 
 

Also, think about where you play: outdoors / woodland may = range and accuracy (hopefully your flat hop mod has achieved this) but you may also want a high rate of fire. 
 

Maybe you play indoors / CQB and in these circumstances people like to have (me included) trigger response. 
 

You can have all of these in one balanced package but that then normally means costing a lot more and whether or not you can do these upgrades yourself. 
 

In conclusion I suggest having a clear idea of what you want and what you can afford. I made the same mistake that many before me and many after will make and that’s rushing into a build and throwing a wad at a sub par gun. Be realistic and honest with yourself. 
 

Ron

[Davegolf]

Aye @RonLancs you don't tune up a 1.6 BMW, you start with an M if you wanna go fast 😁

 

To the OP, most site limits are 328fps for CQC, no point putting a spring in if that's the case.

 

Regardless and said a million times - don't get hung up on FPS.

 

Make sure all your air seals are spot on.

Match your cylinder volume to your barrel and BB weight.

Get a nice barrel.

Dont use cheap BBs.

If playing field use 0.25 or 0.28g BBs.

 

Cheap proper upgrades to your accuracy and range right there.

[Adolf Hamster]

fps is one of many factors in how far you can effectively engage targets, and whilst it's foolish to dismiss it entirely it's equally foolish to think it's the be all and end all of performance.

 

you should start off first with ammo choice, indoors you can get away with .2's as range is not what you need but outdoors you should really be thinking about running heavier (i find .3g is a nice cost/performance balance for assault guns but whatever you can afford to run), quality is very important (sphericity, surface finish, weight and diameter consistency) so cheaper is not always the best route.

 

you've already looked at the hop, if it's a decent bucking and the flathop has been done properly then you shouldn't have too much issue lifting heavier ammo.

 

next is the air seal, no point putting a stronger spring in a gun if it's just going to let all that energy escape rather than shove the bb down the barrel. i have a guide should give you a rough idea of how to go about it:

 

so now you should have a gun that has good consistency, and your practical range (ie the range where you can actually hit someone with an aimed shot not just how far the bb goes) should be pretty decent.

 

now if your a decent chunk under your sites energy limit you can think about a spring change to bring it a bit closer.

 

[Rogerborg]

On 11/07/2020 at 15:58, bluyeti said:

- I have already flat hopped the gun and replaced the bucking.

 

Are you using BBs heavier than those that you could lift with the stock hop?  Good, if so.

 

Just checking, when you say "320fps", do you mean on 0.2g BBs?

 

 

On 11/07/2020 at 15:58, bluyeti said:

I am thinking of upgrading the spring, which one should i buy

 

To get what result?

 

There's no right answer, it entirely depends on the other parts in there and how lucky (or unlucky) you get.  I just threw an "M100" spring into my project M4. Notionally that should get about 1J or 328fps, right?

 

What I actually got from a 229mm 6.02mm ZCI barrel, Maple Leaf rubber in a rotary hop unit, o-ring nozzle and a solid air seal on the stock CYMA piston and cylinder was 375fps, or 1.3J.  Oof.  So I went to an M90 spring which got me down to 340fps.  But it depends which M100, which M90 (I can't recollect the brands) and what you actually see at the chrono.

 

So as above: air seal, air seal, air seal. If you want higher FPS, I'd start with a tighter bore barrel before opening the gearbox.  ZCIs are cheap and seem to be pretty consistent but stocking might be an issue just now.  No need to go longer either - your piston will be ported to your stock barrel length, and as noted I just very nearly accidentally created a Section 5 firearm using a 229mm barrel.

 

If that doesn't get you where you want, only then open the gearbox. I'd fit an o-ring nozzle (get one the same length as your stock one!),  and lube the piston and cylinder head o-rings with silicone (spray, liquid, or I use grease).  Don't get any grease or lube in the piston head ports though, and if necessary, stretch the piston o-ring to help ensure that you've got a good air seal.

 

Put it all back together, see where that gets you (you'll need a chrono), and then and only only then think about the spring based on the best case air seal.

 

 

On 11/07/2020 at 15:58, bluyeti said:

and will the rest of the stock internals hold up- or will they need to be replaced too?

 

If you're aiming for a UK site limit of about 350fps / 1.13J you shouldn't need to change anything.  Maybe knock off the 2nd piston tooth while you're in there, but I can't see the point in replacing functional parts before they're worn out.

 

Just be aware that once you start changing things it might take you a few goes (or in my M4's case a few years ) to get everything working nicely together, so I wouldn't do this on your only gun.