Reply To: O-rings for FX rifles in .22
First, you look at the parts diagram on FX site, here is the link to Impact:
All orings will be metric and will specify hardness of rubber in the description, example: C38 19731 O -ring 2×1 NBR 90
C38 is the location on the diagram, 19731 is internal part number, 2×1 means 2mm diameter and 1 mm cross section, NBR 90 means hardness, Buna 90
So when you go to search for this oring, you go to metric-b90-orings category first, then filter by cross section, 1mm, then find outer diameter 2mm
Also helpful post https://www.airgunnation.com/topic/oring-database-what-im-doing/
Hope this helps.