I started at 3000 psi ( I have a compressor ) and here is my 2027 chrono results.I forget what HS settings other than I was trying for two mags or 24 shots.
I use a Buck Rail 1322 moderator - it is neighbor friendly
If you are not trying to increase muzzle energy, you can also increase the tension of the valve return spring. You can use a heavier spring, or potentially use washers to put more preload to that spring.The theory is to make tank pressure less of a factor compared to the total valve opening/closing dynamic.Given a fixed hammer spring tension, this will decrease muzzle energy because the valve will be harder to open and close faster.Also, based on my own experience down tuning unregulated PCP pistols, reducing hammer spring tension shifts the velocity curve toward the lower pressure side, and it also spreads that curve over a wider range of pressure and still get relatively consistent muzzle velocity. James340's numbers are very consistent with my Brocock AimX .177 PCP pistol despite the Brocock and the Beeman 2027 being unrelated.
This is what mine did. I installed a different hammer spring.The gage on my 2027 reads 100 psi low so 900 psi is actually 1000 psi.Beeman 2027 R10 7.0 4.51 73 mm spring flush 1-2-2023 Chinese crono psi fps 509 1000 499 502 525 532 505 525 532 532 950 545 538 541 554 900 554 551 561 558 571 558 571 568 574 800 591 587 800 594 584 604 610 700 607 700 594 700 600 594 597 594 587 584 600 577 571 568 564 554 551 500 545 538 528 522 400 512 502 495 482 476 300 463
I wanted to get 550/600 fps.I started at 2200 psi and it was shooting 300 with the hammer spring adjusted 7 turns in from flush but velocity steadily went up as pressure went down.it hit 600 at around 1800 psi.I did some HS adjustments and different psi.I get 578 fps to 630 fps at a start pressure of 1200 psi and ending 800 psi and HS adjuster flush with receiver.I wonder if a lighter poppet/valve spring would help to flatten the curve.
FYI finding the velocity knee pertains to regulated PCPs. The Beeman 2027 is unregulated. If it will accept a bstaley O-ring buffer, that's a proven way to produce broad shot strings at modest velocities.
Someone please post a link to the "bstaley O-ring buffer".