I've been digging deeper into the FX Mavericks o-rings and I've found that there are serious errors in both the online schematic AND the schematic they send with o-ring orders. Note: at the time of this writing this may have changed.
The schematic sent has different hardness's i.e. NBR90 instead of NBR70, this makes sense except one is several mm thicker than possible in it's location. The on-line schematic has the old durometer numbers but the right sizes. Numbers below correspond to the online schematic.
13) 10.0 x 1.5 NBR90 inside Regulator hole at bottom of threads use a needle to get this little sucker out
18) 7.5 x 2 NBR70 Regulator Body
20) 4.0 x 1.5 NBR90 End of Piston
23) 4.0 x 1.5 NBR90 Inside Regulator Body, push it all the way in then use a dowel to push it back up and seat it
25) 2.0 x 1.0 NBR90 (2x) Adjustment Screw, suggestion heat in boiling water slip on first one, then second one, or if you have a witches hat it’s easier. And no, heating them doesn't mess them up, they return to shape. I also use the reverse tweezers to stretch them out just a bit, roll on with your finger nails, patience is the key. These little suckers break very easily so.....
Save the pain, buy in bulk from The 0-ring Store a AGN sponsor and they have great taffy too.
I lube ALL 0-rings with light Mobil 1, just a light coat, makes them last a heck of a lot longer, especially if there is movement involved. M1 will not explode in the gun.