I appreciate that. The .25 P15 came to me leaking air and with a bad barrel. I had Lee at Leeairpro machine a LW Polygonal barrel for it. That was when the fun started. The original barrel had an indexing dimple at 12 o'clock to align the barrel and transfer port on the gun. Lee did not put one on. He said to just eyeball it to line it up and the barrel clamps would hold the barrel in place.
I also put in a Huma reg with his power plenum. It worked for several months then the gun started to shoot very erratic over the chrono, so I went back in, thinking regulator. I got nowhere with the internal Huma power plenum, and upon reassembly, the gun was shooting so slow that it would not read at the 590 fps minimum on my FX chrono. I had the HS in as far a it would go to no avail. Finally, I just put the factory reg in which I did not not touch, only swapped out. Same issue. In emptying the gun of air I fired it dry. If you loosen the bleeder screw and re-install it, it will leak. If you loosen the gauge it will leak, and it it difficult to re-align the gauge and still be able to get the fill probe in. I have already experienced those two things trying to fix the original leak when new.
It seems to me, that when I turned the hammer spring in trying to get more velocity, whatever the hammer hits hit so hard it made it shift forward, so now when the hammer hits, what it is hitting is farther away, and so the power is reduced. I don't mind changing an oring or two, but I am not a tinkerer. If something operates properly, I leave it alone. Unfortunately the leaking gun and barrel issue existed as delivered. This is just what I have figured. I could be FOS.