I have had a FX Royale 400 regulated in 22 caliber for 4 years. In the past year I have noticed it has lost some velocity. Say average was 910fps now down to sometimes 885fps. All shot are still very consistent so I didn't think it is the regulator. I changed the breach o ring on suggestion of a member here and that changed velocity just a little to around 890fps. It seams maybe air is leaking around the o ring on each shot. I ordered some 009 Buna-N O rings of 90 durometer. They are pretty hard and a pain to install but it has helped my velocities to be back at 910fps average again for 50 shots. I will see how the long term effect is.