GHK V2 AK CO2 Magazine (5.45 style)

[blobface]

Yeah I think he just misread your message, I did too the first time for some reason. 

[Stuey]

CO₂ sublimes from a solid to a gas. That doesn't mean it doesn't have a liquid phase. The valve still needs to be capable of passing liquid from the CO₂ cylinder into the magazine (more properly, into the capsule) in order to refill it.

 

Er - what? That is the exact opposite of what I said.

 

Dammit, sorry man. Tried again. 

 

CO₂ sublimes from a solid to a gas at room temperature and pressure. is the important bit. Moving on!

 

I really want to get a GHK AK and do a devilhunter, although with these new mags I might not have to.

[Roland1014]

Could this be the next step for GIM replicas?

 

-The shot to shot consistency of CO2 is greater than green gas/propane. 

-CO2 doesn't smell, which is why propane is banned at my local indoor facility

-Filling a couple CO2 tanks is cheap. Even Walmart does it.

 

Just so I understand, you do or do not leave an empty capsule in the magazine?

[Stuey]

Don't forget about less cooldown and better performance in cold weather.

 

I've been banging on about this for years, sort of hoping that a manufacturer or one of our more enterprising members would pick up on it. Unfortunately I don't have the engineering or financial resources to make it happen myself.

 

What do we reckon about the safety aspect? Less fire risk vs. greater asphyxiation risk? 

[Roland1014]

I don't think a single bottle of CO2 is enough to displace an indoor arena's worth of oxygen.

 

 My only issue is I have 5 standard AK74 mags already. I want CO2s, but I don't want the orange shells. Should I buy 5 CO2 mags, swap the shells, and sell the then orange gas mags?

 

Also, how will the internals handle the PSI jump, and what effect will it have on the FPS?

[PureSilver]

Could this be the next step for GIM replicas?  [...] Just so I understand, you do or do not leave an empty capsule in the magazine?

 

Yes, you leave the capsule in the magazine. If you don't, you're subjecting the magazine itself (which wasn't designed as a pressure-bearing vessel and may not even be gastight) to CO₂ at 800psi. That is extremely dangerous; the magazine would probably explode.

 

As to whether this is the next step for GIM guns, almost certainly not. Remember that the capsule was designed to be filled and emptied once, and then discarded. It is categorically NOT DESIGNED or guaranteed safe if you refill it; in fact, if I remember correctly, most 12g capsules will have 'DO NOT REFILL' printed on them. As you fill and empty the capsule, it expands and contracts, causing the metal of the capsule to fatigue. It is for this reason that all CO2 bottles which are designed to be refilled must be tested (usually every 3 years, but sometimes annually) to see if they are still safe to use. Eventually, a 12g capsule - if filled and refilled enough times - will suffer a catastrophic failure. That is simple material science. That failure will release 800psi of gas into the local area of the magazine. Hopefully it won't be in your hand when you do that, but even if it isn't it will have more than enough power to turn the magazine into shrapnel that could maim you.

 

The solution to this problem is to design CO2 magazines that are designed to be refillable, and to be tested like a regular cylinder. However, that would make the individual magazines very expensive - think £200+ each expensive - and that cost is currently considered prohibitive, especially when you'd have to discard them every few years and buy more.

[DEVILHUNTER]

Roland1014, if your mags are GHK with tubes, they will hold the pressure perfectly since the tube of the CO2 mag that not hold the cartridge is the same as the GG mag. The problem is that you will need a CO2 output valve and they are not selling them.

 

If you do the math it can hold a lot of pressure:

 

For example lets take in consideration a mag made with 20mm diameter tubes and 1mm thickness (the GHK are way thicker). Lets use 6061, the most comon aluminium in tubes (7075 is almost two times stronger), it can hold 310 N/mm^2 before break.

 

A 1 mm slice of this tube have 2 mm^2 of aluminium section, and 18 mm^2 where the pressure will make force. That means that you need to do 620 N of force in this 18mm^2 to break the tube.

 

Since pressure is force/surface, you need 34 N/mm^2 of pressure, aprox 340 kg/cm^2. Since CO2 vappor pressure is about 70 kg/cm^2, you are holding only 1/4.85 the pressure you can hold.

 

Now take into account that the tubes are thicker (stornger), and there are much better matherials tan 6061...

 

PureSilver, the fatigue issue does not happen always. There must be a minimal ammount of stress in the matherial to create a small crack, also the cilindrical shape is the greatest to hold the pressure and fatigue is a problem over several thousand cycles that I doubt your mags will reach.

 

Design a mag to hold without any problem the pressure of the liquid CO2 is very simple (I'm making one for my WE M14). For example, the plastic gas line that comes with paintball equipment can hold 12k PSI. The most difficult part is to make a good working and non leaking output valve...

[Roland1014]

So instead of buying new CO2 mags I just need an output valve that can handle the pressure? Are the cylinders the same in both types, except for the piercing and screw cap for the CO2?

[Stuey]

Devilhunter, it's reassuring to see you know what you're talking about, and backing up your claims with maths (not nearly enough of that in airsoft). I'll be following your developments closely!

[DEVILHUNTER]

You need this valve: http://samoon.com.tw/gkm11-4-co2-valve?filter_name=co2 but first you must be sure is compatible with your mag! The new G5 valve look the same and I don't think they will change their design so easy (although the first CO2 M4 mags have other design) .The main problem is that is not going to be made any more and I still don't know if the new mags have a compatible valve. Then change the GHK fill valves with KJW ones.

[Skarclaw]

 

 

The solution to this problem is to design CO2 magazines that are designed to be refillable, and to be tested like a regular cylinder. However, that would make the individual magazines very expensive - think £200+ each expensive - and that cost is currently considered prohibitive, especially when you'd have to discard them every few years and buy more.

 

Why would it be £200? I know they are not the same but you can get co2 capable moscarts for ~$20. I can see the tank needing to be stronger then a propane one but surely it wouldn't need to be that much thicker then existing co2 cartridges/tanks. 

 

 

As for the future of GIM tbh it seems like minor revisions, perhaps less emphasis on emulating the real mechanics and then accepting their downsides. I've been around a bit and never actually read someone selling up their daytona/whatever cause they found the external line was annoying.

[PureSilver]

The problem is the shape - like DEVILHUNTER says, cylinders are by far the strongest and easiest-to-manufacture shapes. Odd shapes - especially odd shapes with corners, which create stress focal points - like magazines are difficult and expensive to make strong enough. The very low volume of manufacture you'd expect - CO₂ capsules are made in their billions, which greatly reduces the price - limits the tooling and production methods you could use, which makes them even more expensive that simple amortization would predict. If a ProWin V2 is £50, I would be surprised if a refillable CO₂ variant would be much less than triple or quadruple that.
 
Refillable CO₂ would be a useful step-up in power for airsoft; I'm personally a big fan of GIM and not of remote lines...

[Rob15]

The problem is the shape - like DEVILHUNTER says, cylinders are by far the strongest and easiest-to-manufacture shapes. Odd shapes - especially odd shapes with corners, which create stress focal points - like magazines are difficult and expensive to make strong enough. The very low volume of manufacture you'd expect - CO₂ capsules are made in their billions, which greatly reduces the price - limits the tooling and production methods you could use, which makes them even more expensive that simple amortization would predict.

Odd shapes with corners, t-slot grooves for the BBs, small rectangular windows in the top for the router and feedlips which also have square corners, then you get to machining the gas chamber itself which is the critical part, the gas chambers are typically long but small diameter bores which makes them troublesome, not an issue for casting.

 

Co2 Moscarts are a bit of an anomaly I think, they're the sort of part that can be made on a suitable CNC lathe quite easily, especially if said lathe has a sub-spindle and live tooling to drill and ream the barrels, the design of them is also very machining friendly, probably because the original Mosquito Molds ones would have been designed to be as easy to machine as possible.

 

As I said in another thread, if people want refillable Co2 magazines then forget ones that are specially made for it, it'd be far cheaper (and this is airsoft, cheaper is virtually always better) to just cast magazines that accept Co2 cartridges as already happens then have a specially made screw in chamber machined to fit each type of magazine with a fill valve in the bottom. Aside from being much cheaper to make to a high standard this would allow people to continue to use 12g Co2 cartridges if bulk Co2 refills aren't readily available and potentially make existing Co2 magazines convertable.

 

The above is the sort of product I'd love to make, however the cost of developing a product and having it tested properly in line with UK and EU laws so my insurance policy would cover me if one did go wrong means I probably never will, there is no shortage of products for me to make where development costs are lower and failure won't cause personal injury.

[DEVILHUNTER]

Other option:

 

http://www.khmountain.com/airsoft/product_info.php?products_id=4643
http://www.khmountain.com/airsoft/product_info.php?products_id=4644

 

It's not the best way in my opinion, but should work and it's not too expensive.

[blobface]

troublesome

 

Hence the King Arms stainless steel insert for the Tanaka M700 magazines are $240 a pop... 

[PureSilver]

Other option:

 

http://www.khmountain.com/airsoft/product_info.php?products_id=4643

 

I think I'll pick up a couple of these, thanks! I think I can modify the KJW CO₂ magazines I use in my P226 and the GHK CO₂ V2 STANAGs (boy that's a lot of capital letters) so I can access the fill port without having to remove the capsule from the magazine.

 

[EDIT]Plus, I could use these on the Begadi CO₂ rig for the G96... Interesting![/EDIT]

[Stuey]

[manufacturing stuff]

 

Do you think you'd be able to make something like those PPS cartridges? (link) Fairly easy shape, for the GHK mags they wouldn't even need the fill valve on the bottom (just maybe a big fat o ring on top for a good seal).

[paranoiddroid]

Ok so if there's someone I can find to do the conversion for me out there let me know!!! Mommy NEEDS reliable m4 mags

[Roland1014]

I am considering coughing up the quid to equip each of my mags with one of the CO2 vavles. Are we absolutely sure I'm not going to blow out my $50/ea magazines?

[Stuey]

Absolutely not sure! Do it at your own risk.

[Number5]

Beautiful work here gents. These needs a home inthe technical thread

[paranoiddroid]

Other option:

 

http://www.khmountain.com/airsoft/product_info.php?products_id=4643

http://www.khmountain.com/airsoft/product_info.php?products_id=4644

 

It's not the best way in my opinion, but should work and it's not too expensive.

Is that a Co2 to gbb converter basically? So you can use a Co2 mag and fill it with green?

[Stuey]

You probably could do, but you'd hardly get any gas in there. I believe it's so that you can refill a CO2 mag using a larger CO2 source (like a paintball bottle with a Madbull adapter), essentially allowing the CO2 mag to be used in the same manner as a normal gas mag (but with CO2), eliminating the need for disposable 12g cartridges. Certainly that's why a bunch of people in this thread are excited about it.

[Rob15]

Do you think you'd be able to make something like those PPS cartridges? (link) Fairly easy shape, for the GHK mags they wouldn't even need the fill valve on the bottom (just maybe a big fat o ring on top for a good seal).

They'd be easy to make, especially if no valve is needed but it's the potential issues around having them tested and certified properly that would be the difficult part. If I was located in the US then I'd be more inclined to look into doing parts like that, manufacturing costs are typically lower and they have far easier access to bulk Co2 refills than here, combined with being a much larger country would make for a much bigger home market to make it worth the investment.

[Reppyboyo]

Got one of these with my new 74U.
Good mags, fairly efficient and a lovely kick.
CO2 bulbs tend to get stuck sometimes is the only downside.