CO2 Magazine Nut

Okay guys, I’m aware of the two different magazine nut designs for the APS CO2 magazines. Using the original design, I have perfected the process of fitting the nut without destroying the o-rings, however I still consistently have the outer o-ring pop out which subsequently gets destroyed when removing the nut, despite having purged the remaining gas out of the magazine. There is still enough remaining pressure trapped between the two o-rings to cause it to still pop the outer seal.

Does the new design prevent THIS SPECIFIC issue from occurring?

are you keeping your finger on the valve while unscrewing the nut?

you still need to do that with the 2 piece nut to make sure there is no pressure in the mag when your unscrewing the base.

Yeah mate, I am doing that sorry. That process doesn’t purge the trapped gas between the inner and outer o-rings though

ah ok, havent noticed that. in that case, yes the 2 piece ones should prevent that. you’re completely screwing the outer cap in first before piercing the bulb with the inner piece so shouldnt be getting any gas between the o-rings

Yeah mate, I was thinking something similar but just looking for confirmation based on first hand experience from someone if possible.

ive got the 2 piece ones in my mags and havent had any dramas with the o-rings. I did screw up a couple of orings on the originals screwing them in. Other than that the main problem i had with the originals was amount of force needed to screw them in enough to slide the bottom cap on.

I dont have the answer mate… and I’m really struggling with this whole ‘special nut’. It’s an obvious engineering flaw that we paid top dollar for. But that’s ok… we can be excited and pay more for a solution?

I expected more from an industry leader.


Hi mate i have the stage 2 design mag base cap thingo whatever its called. Ive put about 50 mags through it and still managed to go through 2 o rings. I was always really careful and purge the mag when opening the cap. I rekon it just comes down to general wear on the o ring when inserting/removing. Its common in the a/s world that this design is bad for o rings.

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Tac edge have some available now :+1:

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And don’t forget BUTTSMARN for discount.

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As much as I hate the idea of paying to ‘improve’ something I just bloody bought, I picked up 2 of the new caps so I could do a review on YouTube, will compare and see what is improved and what issues still might exist etc.


I’ve been using the new caps for a couple of days now and they are an improvement over the one piece caps.
They don’t seem to be able to pierce the bulb as much but that hasn’t changed the performance at all.
I never really had problems with the old cap as long as I was careful but the new ones are definitely easier to use.


Has anyone had issues with gels not firing 100% of the time? Sometimes mine will just shear half the top gel off or just not fire it. Is this a CO2 issue or a mag seating issues?

Mate that would be great if ya could. I will probably buy a few anyway but a good review will solidify my decision.

What gels?

AKA ultras

Yeah ok, which pistol? My APS Shark does AKA gels nearly perfect (AKAs not Ausgel Ultras). The Warinterest ones sometimes break while firing and cut in half under the spring force in the magazine, so they are just for my AEGs.

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It’s an XTP. And yeah mostly it goes perfectly, but sometimes it just doesn’t seem to be feeding.

I’d probably check the mag for sharp bits around the area where gels feed up, then maybe try a different mag. If that doesn’t work try a different batch of gels. Then at least you’ve ruled out everything until you need to start ripping apart your XTP.

did you read this post may help