Help: Artemis M30 Regulator under-filling?

[SnowblindOtter]

I have an Artemis M30 by SPA that I picked up a couple of years ago, and up until the beginning of this year, it's been working fine. Very consistent, very reliable, very accurate. Recently, though, I've been noticing that the regulator gauge is showing that it's not recovering to its set point(110bar) fully after a few shots, despite being set to less than half the tank's fill limit, and my groups have gone to all kinds of junk. I've torn my rifle apart, pulled the reg out, changed seals, degreased everything, re-lubed each and every spring washer individually, and put it back together exactly as I found it, then refilled it with the regulator set to 0 to raise it up to 110bar. Doing that helped marginally, but it dropped the discrepancy down from a dramatic 20bar per shot, but I'm still not entirely happy with it right now.

I shot these strings a week ago trying to get help from some people on Reddit, but I haven't heard anything back from them at all, but this does see to confirm the idea of the regulator creeping down each shot. All shots were with H&N Barracuda Hunter Extreme .22cal pellets, which I sort by weight. Each pellet in this set weighed 18.52grains.

String 1:
834fps
827fps
824fps
822fps
822fps
817fps
780fps
758fps
814fps
803fps

Spread of 76fps and SD of 22fps. Shot normally for sighting in, which is just casually shooting about 1 shot every second or so. I was shooting 'fast', but I was not in a hurry.

String 2:
833fps
831fps
828fps
826fps
818fps
828fps
823fps
816fps
825fps
815fps

Spread of 18fps and SD of 5fps.
Second string shot with a 3-4 second pause between each shot, around the time it takes to lower, cycle, shoulder, aim, and fire while taking my time.

Across these 20 shots, the regulator gauge says that it dropped 10bar. It never creeps up while sitting idle. After shooting those strings I haven't touched my rifle, not even to fill the tank, in a week, and the tank pressure has not climbed according to the gauges. The regulator only climbs when I fill it, which I understand is normal. Can anyone give me any thoughts on this? Would you call behavior like this normal and I'm just overreacting, or is this unusual behavior and I am right to want to fix this?


Note on my strings: Due to financial reasons I don't have a proper chronograph just yet. I'm relying on the ChronoConnect Mobile app on my phone to estimate things while I budget for even an inexpensive one, but I've validated trajectories in Strelok Pro using numbers it's given me to ±5fps with different rifles. I think anyone can agree that margin of error coming from my phone's built-in microphone is more than acceptable for basic ballistics and monitoring the health of an airgun.