Yeah I’m with Emu and the rest who feel that measuring the old o ring gets you what you need.
There are FX haters, and to those I have to say, FX is so service oriented like no other manufacturer. Sure, other makers of PCP’s offer drawings also, but fx provides drawings for days along with part numbers, o ring sizes/types along with fastener sizes.
What I do wish, for the manufacturers that don’t go above and beyond like FX does, is at least follow what Hatsan and LCS does and provide an o ring kit in the box for each gun they produce/sell.
Since we’re on this topic, what other pcp manufacturers provide an o ring kit with each gun? I only know of Hatsan and LCS as that’s what I own. Does Edgun, Daystate, Steyr, etc provide seals? Let’s name them if you know of other makers that provide a kit with each gun