O-Ring size question

What size is the o-ring  on a Crosman Mk1 on the fill cap.  If it matters, this one is a lever cap.  What type of o-ring do I need?

Thanks,

David Enoch

David been looking for the sizes and found this-----now the larger o'ring is the same on both early and late models

the toggle piercing cap has a small o'ring that is part 600-84 or 084 but I haven't found that size yet

https://forum.vintageairgunsgallery.com/crosman-pistols/crosman-mark-i/#post-1977

this info is worth reading anyway o'ring sizes are mentioned and any o'ring that is touched by co2 should be urethane all other o'ring material will absorb co2 and swell, some worse than others

I posted the question on the Green Forum also, of what size is part number--o'ring 600-84 is

just handy info to have

Thanks for the help!

David Enoch