Gotta say that I’d be pretty gutted to drop 1800 and find that the gun can only shoot GTOs at 19fpe. There’s gotta be something wrong with that one. Did you check if it was intended to be running 165bar?
I have a hunch it's tuned way to hot. There are a lot of folks here who think faster is better and at one time I was one of those people. However, I have come to realize that too fast can be very inaccurate [IF] accuracy is a priority?