AEA Anybody know what causes this?

No, I don't use any tools except for removal. I install the o-rings simply by rolling them onto the 'thinner part'(?) which goes into the receiver.
@MOhunter I didn’t think so, but thought I’d ask because it hadn’t been mentioned. Those groove surfaces look chamfered in the photos. Let us know what you find.
 
What size is that Oring.lol, i have a JTS one that is the same rebranded, it is slow to get up to pressure, but always gets there.
Apologies for not seeing your reply.

The GX CS3
Whip hose swivel O rings: #111 (requires two) OD- 0.370”; ID- 0.140”; CS- 0.070”

The Foster coupler "O" rings (2) #010 (universal inch size O ring number)

I often find that I have an inch sized O ring that will work for metric applications, or vice versa.

In case someone doesn't know, inch sized common O rings are designated according to a number system, while metric by their dimensions.


 
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So I've got an AEA HPSS Plus in .25. I replaced the puppet valve and realized I couldn't get it to fill anymore. Once I took some soapy water to it I found out it was leaking between where the pressure tube meets the housing on the rifle. So it took it apart and found a big gash in one of the o-rings. I don't understand what could be scraping these that causes this. I take the grub screw out far enough that's not an issue and of course the pressure gauge is already removed I'm just stumped. And I just noticed one of the new o-rings I installed already has a cut in it. What the hell? Anybody got any ideas?View attachment 569571



View attachment 569570
You need to source a new o ring. Definitely use silicone grease on the o rings when you are sliding it back together it will help prevent cuts. Check for sharp edges first
 
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You need to source a new o ring. Definitely use silicone grease on the o rings when you are sliding it back together it will help prevent cuts. Check for sharp edges first
Well long story short, I did need new O rings and was able to have a friend, who had them, who helped fix it. It was also leaking out of the air pressure gauge, which he fixed. No, I could not find any sharp edges no matter how hard I looked. I might have been the angle it was installed/removed. But I don't fully think so. I think it was old o-rings?
 
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