Hi Pete,
The valve pin o-ring is 4mm X 1.5mm
the Probe o-ring is 2.5mm X 1.2mm (they provide the same size for both calibers... )
This info is available in "the 850 Resource index" under "850 service and modification infomation"
there is a downloadable exploded parts diagram with part numbers and o-ring sizes on it.
I would try something a bit fatter for both though. obviously reducing the diameter accordingly.
I hope this helps?
Roald.
The 850 Store
