OK, I I've done it. Got my cylinder regulated to 125 bar.
You need 13 mm wrench, and a friend that has bench vise
. We used some kind of leather to save the surface of the cylinder, when inserted into the vise. Just light taps with the hammer on the wrench got it loose enough, to be unscrewed by hand. Then we inserted the regulator in the tube, the top part in the picture first, then screwed back in the valve body. And that was it.
Then I tried to hand pump the cylinder. No luck. It was leaking air through the valve. Googled it, but I didn't find the solution how to do it. Then, on YT, i saw some Spanish dude video on hatsan regulator, and somehow I I've figured out that I need to pump the cylinder back to 50 bar, to stop the leak, and that I had to use that degassing part that came along with at44 to stop it leaking while i get to 50 bar (Teflon tape helped me out, to seal those two holes on degass-er, I used a big needle wrapped around with Teflon tape to close that small hole). No one tells you this!
After I got beyond 50 bar limit, leaking stopped. Now, I have regulated AT44. It got dark while I did this and shot chrony, so I will have to check grouping and accuracy tomorrow.
These are shot strings with JSB 13,43 grain exact jumbo RS pellets.
Before regulator, from 195 bar to somewhere bellow 100 bar, 30 shots
After regulator, from 195 bar to 100 bar (you will notice the spot when pressure went bellow 125 bar) 30 shots
it looks like I have 22 regulated shots
and there is no need to drill a hole on a cylinder body, and gauge reads true pressure inside cylinder.