FX Impact mystery oring in magazine.

This is ridiculous. I’m shooting my Impact tonight when suddenly things felt strange chambering a slug. Pulled my mag to see how many slugs I had left and noticed an oring inside my mag. Thought no big deal it’s probably my probe oring. It’s not. Probe oring is fine. I measure it and it’s 5.5x1.5mm. Look at the parts diagram for my gun and the only 5.5x1.5 is in the valve tube end. You can see the oring is worn but since I haven’t taken the gun apart yet I’m curious if anyone else has had this issue. In the second pic the oring in question is 25.1. 
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The gun is almost back together. It’s sitting with air in it to see if it has any leaks. The best I can figure after staring at that oring for a while is it had to come from my Kral. It blew a probe oring a while back and it looked like that. Maybe when I was filling the mag I sat the mag cover on it and the silicone residue from shooting slugs made it stick. Still don’t know how I didn’t see it when I put the cover back on and clicked it. If that’s the case, I feel like a fool. At least I got to look inside the gun and lube stuff. Crazy.
 
My mag started seizing and I toke it apart, when back again I found that oring as well. Toke apart my second mag only to see where this thing shall sit and no oring in the second...

but what I noticed the spring wire OD in both is different, also one is carbon steel the second is SST and this SST spring is softer so exactly that mag tend to stuck with loaded pellets I need to plink with my fingers to make it move to next pellet - sometimes.