Success! While I am not fully sure about what exactly went wrong, it seems that I just need to press quite a bit harder with this new propane cylinder (same brand, almost same age due to labeling.) That could be why the other tank ended up leaking, some defect making it easier for propane to come out (which would explain why I got used to pressing the propane tank more lightly. With a full fill, I got 63 full powered shots off, which really surprised me, as I was previously doing three 2 second fills, which gave it about 38 shots.

Thank you all, for you have helped me immensely!

I've have 2 KJ Works M92, bought them in 2005, last use was in 2006 maybe 2007. There hasn't been any gas in it since then, due to the loss of my adapter, so what should I do? Since you said that my mags will probably be leaking gas...

You could try to necro them like you did this thread... ba-zing!

But seriously... probably buying new ones is easier than trying to resurrect yours (I'm assuming that your KJW mags are leaking, correct? Or do you not have a propane adaptor yet). New ones from overseas at $20 USD a piece, plus shipping. Brand new from most retailers, they can be found at $40 a piece in Canada. The choice is yours... there are just too many possibilities for potential dried up/cracked rubber bits to warrant trying to fix them, IMO.

You can always take them apart and check the o-rings and seals yourself and give them a good dose of silicone oil before you fill with gas. They're usually held together with body pins, press them out and you're on your way. You can also take the valves out (screw driver works but a valve tool is best) and lube the o-rings on them. The intake valve can also be taken apart; the bottom will unscrew from the top (the bottom will have a tiny spring and the top will have a tiny o-ring on the valve -- Don't lose any pieces). Once you start into it, you can see what pins come out and what's molded for looks... Don't be scared of it - juicy wants you to replace the mag anyway, right? What's the harm of dissembling the mag and trying to resurrect it yourself...

True. It's worth looking into... if you know what you're doing. Or hell, if it doesn't work or you can't put it back together, voila - two parts mags for shiny new TM ones! :D

Go to hardware store, plumbing department, buy a pack of Spout o-rings, they usually come in packs of 10 with varying sizes, try replacing the stock ones with some of these, start with one that looks similar to yours and work from there until it no longer leaks.

+1 You can also try farm and car parts stores. I was able to find all the o-rings I needed with the exeption of the fill valve o-ring - too small.

You can also use silicone gasket maker, a thin coating around the offending rubber piece and your leak is history; available at Canadian Tire or others like it...

Heh, I went to Princess Auto and bought a pack of 250 or 300 o-rings of different sizes, organized into group of size 1, size 2, etc. That's got to have the right size.