After looking over the Forum for the o rings required for the FX impact, and all the different models and calibers. I made a complete list M3 back to the Impact X. Including the 0.35 caliber barrel. There is a “BUNCH” that overlap with all of Impact versions. Thanks “texagdds”… his topic gave me a lot of the replacement part numbers and where to find the missing ones. If I left some out let me know so I can include them. Updated 11-13-2021