According to the manual, they operate at 120 to 300 bar, while EDgun Wests' website says they operate at 120 to 250 bar. I currently fill to 300 bar and shoot through 4 magazines, which brings the pressure down to ~130 bar.
I don't see the need to continually stress everything, I normally go to 250 bar, that's plenty. An extra 3 or 4 minutes for an additional fill isn't a...life time !! Just shot mine yesterday after a bit of a quiet period ! Still holding air quite well.
When I had mine I always filled to 250, I don’t fill any of my 300 bar rifles to 300 only fill to 250, all ya get going to 300 is a few more shots, more strain on the regulator, etc…