Do gas mag fill valves require orings?

[tylamarre]

I ordered new orings for my marui pistol mags because they do not come with any. I'm talking about the part that you can see where you insert your green gas or propane adapter into. The ones I got are supposed to be the right size and material (Buna 002-70D) but I can't get them to fit.

So my question - are these necessary or will replacing my propane adapter, the madbull cnc one, with a softer material fill adapter like the Airsoft innovations Abs one solve the problem of gas spraying out and mags not filling all the way?

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[tylamarre]

Follow up question, what grease is best for airsoft pistols? I have silicone oil but I'd like to try a grease instead and maybe put some on the fill valve too if I don't find a solution for the oring.

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[RainyEyes]

Yes... Those are standard o-rings where you put the gas adapter to fill the magazine to serve the purpose for why it's made... You aren't supposed to need to buy them separately.

May I ask where you bought them? How are you trying to install the o-rings so that they "fit"?

The only o-rings that are aftermarket are sequential's silent fill o-rings and they're meant to prevent leakage like you described. I think the ones I have are similar to his but not sure if they're 70D.

[Windows]

Marui mags are supposed to vent out the fill valves while filling. This ensures a full fill every time.

[tylamarre]

I don't think it's supposed to vent while filling. Maybe once it is actually full. Those mags that vent are never able to get through a full mag. I've been wrong before but I don't think gas is supposed to be spraying everywhere when you insert the propane adapter.

The orings I bought were from the McMaster-Carr catalog but I got them cheaper through ebay. Measured them with my micrometer and they match the specs on the catalog.

I got this information from a couple different forums and YouTube videos, some of which mentioned their marui mags did not come with orings either.

I'll check out the sequential orings.

[RainyEyes]

How are these mags retaining gas if they don't have o-rings inside the fill valve?

Again, how are you installing them? These are o-rings inside the magazine... Not the outside.

For pistols the best grease is white lithium grease for the metal parts or another silicone based alternative. You gan generally get away with lithium grease not eating away at the plastic parts and it's generally inert for most parts.

[tylamarre]

Right sorry, forgot to say how I was installing them. These aren't the internal orings that retain gas, it's the tiny ones on the outside that seal against the propane adapter. Sometimes they fall out on their own as they're only held on by friction. I'm installing them by using a toothpick to place it level and center on the nipple and using a propane adapter to push it onto the nipple.

I suspect there are a few different sizes used on gas mags as these ones worked for other people but not for me. They are too thick so even when I do manage to get them in there nicely they cause the nipple to stick and gas to leak out.

I'll try to buy some orings today from my local shop and if they fit I'll post what measurement they are and hopefully a bulk catalog number.

[Windows]

Marui valves are supposed to vent gas (not liquid)
in this image, you can see a small hole near the threads of the fill valve. This to to allow the gaseous portion of the propellant to escape out the side of the fill valve while the long tube allows the liquid portion to dispense out the bottom. When filling, you should get a small spray of gas coming from the fill valve. When the mag is full, this spray will turn liquid, letting you know that the mag is full.
As far as I know this feature is only present on TM gas mags.

[tylamarre]

Okay so that hole doesn't vent outside the mag but rather the gas that leaks when filling will go from gas to liquid to show its full of liquid? Hey that's pretty neat!

Are all marui mags like that?

I think I still need a new propane adapter but I might be fine without the orings?

[Windows]

The little hole inside the pressure vessel connects to a vent located around the central fill port on the valve and vents outside. This hole is very hard to see and is normally blocked by an internal seal so that the gas only vents out when you're filling the mag.

If you've ever had large BBQ style propane bottles filled this function is done by a small brass valve that the filler has to open manually. (spit 80% valve in this picture) TM fill valves have this functionality built in.



All TM mags have this, and as far as I know, only TM mags have this.

[tylamarre]

The nipple pushes in a bit when filling, is that where the gas releases? Is that seal spring loaded or is it held there just by the gas pressure? I thought before that the gas I was seeing was coming from where the adapter seals against the nipple but this explains it better.

[Windows]

Precisely, the nipple on the filler pushes down and opens a seal on the bottom to allow the liquid in, while simultaneously opening another one on top to allow gas out. It is mainly held in place by gas pressure, but there is also a spring which is meant to seat the seals if there is no pressure.

You should only see liquid coming out if the, magazine is (~80%) full, and your filling. If you know the magazine is empty, and and liquid is spraying all over the place, it's usually a faulty adapter, or incorrect alignment. Metal adapters are especially susceptible. However sometimes the internal seals in the valve can be old and worn out, in which case you may be able to hear gas escaping through the fill valve as a slow hiss. In which case the best course of action is usually to replace the valve.

Follow up answer: any lightweight grease that doesn't react with plastics or rubber should work. Some gun lubricants such as frog lube are a good choice, or white lithium (tube, not in a spray can) and molybdenum disulphide based greases are also popular.

[ThunderCactus]

To summarize, your fill valves are working exactly as theyre supposed to.