[Automobilie]

Comparison between poor-sealing stock mag rubbers and better fitting 9-Ball rubbers. Gun is a KJW hicapa.

Using an adapter for compressor air, with stock seals the pistol requires over 100 PSI to fully cycle the slide back to lock. With the replacement seals, it does the same at 70 PSI.

Propane at 60F is about 90 PSI, which explains why the gun worked so poorly before.

 

[Ben3721]

Maybe it's just me, but 3 years ago I bought 4 nine ball m9 gaskets. They came shrunken and dried out with a thick film on them from drying out. So I've avoided their rubber parts since. I probably got a older stock.

I will say however, certain pistols like the hi capa have a tendency to damage the back middle section of the gasket over time from the bb feeding bar on the nozzles rubbing them before it reaching the section that seals. Tends to take a bit out of it after awhile. Even stock tm nozzles do it. It's easily fixed with slight modification to the nozzle, but still annoying, most wouldnt notice such a petty thing tho.

Honestly, I've seen more than gasket condition/height effect the seal to the nozzle. I've seen nozzles with different dimensions screw over the seal, seen aftermarket blowback housings with different dimensions mess with the seal, worn out mag catches, and lastly grips that have too much slack allowing the magazine to fit poorly... Not to mention a old gbb having its rails and slide wear out increasing the gap. There is the option of gasket spacing if one is desperate. Another thing that probably doesnt help squishing seals is leaving the magazine in for months of storage.

Its sad how many kids run their gbb guns with no knowledge on how to maintain or improve them and just spit gas out.

 

[Guges Mk3]

80% of the Airsofting Public truly have no clue on proper maintenance of Airsoft items.

 

[Nineball69]

I bought a set of these for a KJW M1911A1 (609-GAS). While they were in great shape and did stand taller, it just wasn't enough. High vacuum silicone grease around them, nothing. They mated up perfectly with the nozzle. Excellent compression, but only five shots before going from 60 to zero in 4.3. They did work fantastic for sealing on a Tokyo Marui HCX45. I was impressed.

 

[Automobilie]

If you're only pushing 5 shots and it isn't purging liquid that sounds like the mag isn't filling. KJW just uses regular fill valves, which are a PITA to fill reliably. The TM venting valves are probably my favorite.
That's why I like the compressor setup, rules out problems from filling.

 

[Ben3721]

Tokyo Marui fill valves leak some of the gas (not liquid) out of a side vent in the stem as your filling them, this allows you to fill them up to the proper level, which is limited by a tube inside. It needs to have some of the propane as gas to prevent the mag from spitting liquid propane, room to expand so-to-speak.

However all other brands use sealed fill valves, which still do have a tube inside to limit the amount of gas. Which require you to purge the mag of normal air to fill it to the proper level by just using it a few times or holding the knocker valve open while filling it for a few seconds.

I hope I'm accurate on the first part about TM's. @Guges Mk3

 

[Automobilie]

That's pretty much right for the TM venting valves. The gas leak let's the pressure in the mag stay below tank pressure so that it's always pushing more (liquid) into the mag until the liquid hit's the stem.

The other valves though (or when people stick o-rings in the venting valves) don't have the pressure drop, so as soon as the mag pressure is the same as the tank, they basically stop filling. I don't think I've ever had good results from non-venting valves.

 

[Ben3721]

That's pretty much right for the TM venting valves. The gas leak let's the pressure in the mag stay below tank pressure so that it's always pushing more (liquid) into the mag until the liquid hit's the stem.

The other valves though (or when people stick o-rings in the venting valves) don't have the pressure drop, so as soon as the mag pressure is the same as the tank, they basically stop filling. I don't think I've ever had good results from non-venting valves.

I've found if your able to get and keep air out of the magazine which is harder to compress than propane, then things will fill just fine. If leftover propane gas is in the magazine it will compress. However using a o ring in a tm mag doesnt just convert it properly... as non venting dont have a side vent AND also have a o ring. Well tm makes arent made for propane really to begin with...

This reminds me of a new co2 tank, which it takes a purging to get the most air out before first filling or risk rupturing the safety cap.

 

[Guges Mk3]

It's all about PV=nRT in moving gas back and forth in a tank.

No "Air" ever get's in a mag unless it's "put" in there. That purging you describe doesn't truly "purge" a tank. It's about reducing temp to drop pressure and changing the state of the CO2 in the tank. The only way to "purge" a tank that is a closed system is to put it in a vacuum chamber...much like an HVAC system that has it the coolant changed

Plus you can't over fill a CO2 tank to cause it to rupture. That Disc is rated for ~1800psi. However, if you fill a CO2 tank and you hit it with heat or sun light then the temp increases which means pressure increases and the rupture disc blows for safety. You can however "Force" more gas in a lower energy state into a tank...but why would you want to make a pressure cylinder "bomb".

Plus not to mention...not a lot of devices can release a 1800 PSI pin valve and then...I wouldn't want that level of pressure to to hit an item that can't handle it...

 

[Automobilie]

I had tried doing the math on how much space you lose from an air bubble (should compress at about 90psi) and it wasn't much more than 20%, but that's if I remember my numbers from years ago.

 

[Automobilie]

What would be really neat to see filling a clear "mag". Basically a plexiglass box with clear sides and compare different fill valves, techniques, effect of air, different gas, tempersture effects, etc.

 

[Hyperslow556]

TIL!

 

[cetane]

What would be really neat to see filling a clear "mag". Basically a plexiglass box with clear sides and compare different fill valves, techniques, effect of air, different gas, tempersture effects, etc.

that would be simple to rig up with a piece of pyrex sight glass and fittings. 3/4" iirc is good for 250psi.

 

[Ben3721]

It's all about PV=nRT in moving gas back and forth in a tank.

No "Air" ever get's in a mag unless it's "put" in there. That purging you describe doesn't truly "purge" a tank. It's about reducing temp to drop pressure and changing the state of the CO2 in the tank. The only way to "purge" a tank that is a closed system is to put it in a vacuum chamber...much like an HVAC system that has it the coolant changed

Plus you can't over fill a CO2 tank to cause it to rupture. That Disc is rated for ~1800psi. However, if you fill a CO2 tank and you hit it with heat or sun light then the temp increases which means pressure increases and the rupture disc blows for safety. You can however "Force" more gas in a lower energy state into a tank...but why would you want to make a pressure cylinder "bomb".

Plus not to mention...not a lot of devices can release a 1800 PSI pin valve and then...I wouldn't want that level of pressure to to hit an item that can't handle it...

Maybe it's best to keep the co2 talk apart from the propane, they are too different. .. You are right about the co2 tanks.
When a green gas magazine is new or if you take the bottom off, normal air gets in, which is harder to compress than propane gas normally left over in the magazine. Every time I take down my magazines they tend to have a lot less volume for the next few magazines unless I bleed propane through the mag. Which helps a fair bit in my own experience.

 

[Guges Mk3]

Maybe it's best to keep the co2 talk apart from the propane, they are too different. .. You are right about the co2 tanks.
When a green gas magazine is new or if you take the bottom off, normal air gets in, which is harder to compress than propane gas normally left over in the magazine. Every time I take down my magazines they tend to have a lot less volume for the next few magazines unless I bleed propane through the mag. Which helps a fair bit in my own experience.

^ Which is an additional level of detail that is not commonly occurring with "normal" use of a mag.

Much like I could say...I do mag rebuilds via robotic arms in a vacuum chamber so I don't have this issue... First mag fill literally suck in way to much liquid gas.

 

[Ben3721]

^ Which is an additional level of detail that is not commonly occurring with "normal" use of a mag.

Much like I could say...I do mag rebuilds via robotic arms in a vacuum chamber so I don't have this issue... First mag fill literally suck in way to much liquid gas.

I highly recommend cleaning brand new magazines, I have had a couple TM and WE mags with metal shavings from tapping the screw hole out straight from the factory, I dont want to even thing of all the damage that can cause... Guess mass production doesnt care about quality.

 

[Automobilie]

Anyone have a mill to put together a little test jig for us?

 

[kazuchan]

I see a old guide before with make a slim/thin plasic sheet add below the gasket to make it "higher" , more contact with loading nozzle.

Is it still good for these days?

 

[Automobilie]

It is, although it doesn't always work well enough.
I'd like to figure out which rubber they use on these seals, because some rubbers can be cast at home with a 3D printed mold.