I have a WARP and you have to be
venting the regulator to adjust to a lower pressure or you will damage the regulator. You do not need to depressurize the bottle although you are losing some while you adjust. I adjusted the regulator to 2900 then shot the gun down of reg to 1500, chronographing every shot to get a curve and recording pressure at each shot. Then I set the pressure to the FPS I wanted which was 850.
Absolutely, contact Jim at WAR, he is a great guy and will answer your questions.
Here is the procedure (which by the way I just called Jim a minute ago and double checked/confirmed just for you!):
To adjust the Cobra regulator to a lower set point, SLIGHTLY unscrew the burst disk on the regulator til it's hissing a bit of air. THEN screw the set screw on the bottom of the regulator IN (NOT OUT!, setscrew 'out' increases the set pressure). Better to go too much than have to do it again.. Then tighten the burst disk to stop the 'leak' NOTE: don't OVER tighten or after a couple of times you will have to replace the disc. Then fill the bottle and adjust the set point to what you want. I do it in a couple of steps and chronograph the test shots to tweak the set point to exactly what I want {Diabolo pellets do not like over 900 FPS in my experience} You do NOT have to loosen the burst disk for increasing the set point, only lowering it.
and here is my WARP
and here is my custom .357 FLEX+ with titanium air tube and prototype collet barrel retention system so can really tension the barrel. This is a long range very accurate airgun, less than 1 MOA at 100 yards and 4" groups at 300 yards! I should also add that an owner should not set the Cobra regulator above 3000 PSI as it could damage it. My FLEX+ has a custom regulator that sets at 3400 but it took Jim reworking the internals to do that!