What is the correct location for this o-ring (r/t classic valve)?

[The Ritual]

I'm not sure if this reg seat o-ring is supposed to be placed in the brass reg seat holder, or in the recess of the rear half of the valve. Pls see pics.



I've been placing it in the brass reg seat because that's where it was located when I disassembled it for the very first time, however...


...it keeps ending up here after a few shots.


Does it belong in the rear half of the valve?

[OPBN]

Is it leaking ?

[Tunaman]

It goes in the back of the valve

[Cyco-Dude]

in the reg body, but it'll move. make sure it is clean and well-oiled.

[The Ritual]

Is it leaking ?

Nope, no leaking issues.

It goes in the back of the valve

Thanks! That is exactly what I needed to know.

in the reg body, but it'll move. make sure it is clean and well-oiled.

That's what confused me, as I didn't expect it to move. Thanks for the advice