In my .25 cal. Crown, I have the simple 2018 Power tune kit from Ernest Rowe - FX and can reach 1000fps with the 25.4gr. JSB's and 885fps with the 33.95gr.JSB MkI's. My regulator is set a little above 150BAR, somewhere in the 153-154BAR range. The kit gained me about 30-35fps but that can vary depending on gun. If you are willing to buy the 2019 power tune kit from FX, which is a lot more comprehensive, power increases should be more substantial.
My chrono readings without the power tune kit, my reg. pressure set at 150BAR and my hammer spring tuned for maximum velocity were a little higher than most of the other results I've heard of from other Crown owners but there have been a couple of posts I've read where Crown owners had even higher velocities. I couldn't reach 900fps with the 33.95 JSB's but it might be possible.
One other thing... I've read many times that turning the reg. pressure past 150BAR can be bad for your gun or not advantageous without rearranging the Belleville washers. I've been told by two of the top people at FX that this simply isn't true. I really don't know who to believe or if it's true or not. I can tell you though, I've had my gun adjusted as high as about 158BAR for a while and then set at 154BAR where it's currently set and has been for a while without any problems. I have a slug liner coming any day and if it's necessary to turn my reg. pressure up, I won't worry about it one bit.
Keep in mind that velocity is nothing without accuracy. I too have tried to achieve 900fps with the 33.95's because when I install my slug liner I'm going to be shooting some heavier slugs and am hoping they'll shoot well at higher velocities. If they don't, I'll either shoot a lighter slug or turn the reg pressure down a bit. For me accuracy comes first, velocity/energy second. Good luck!
Oh, one other thing, the gauges on these guns from the factory aren't the most accurate, but these numbers I've quoted are the numbers my gun shows. I hope this helps a little.
Stoti
