Priest 2, can't reach velocities others can?

Sounds like your gun is good to go. 935fps with a 25gr pellet and a 150b reg setting. That’s nothing to complain about.

Sorry, made a mistake. 258m/s is 846fps.

I wish it was 935fps @150bar, this topic wouldn't have existed then. ;-)

The Slovenian guy on Youtube who does a lot of Priest reviews is getting 895fps.

50 more than me with the exact same configuration. Altough, his barrel is different in that video. I think he uses the stock .22 barrel from CZ. I have the LW .22 "long range" barrel.

Two completely different barrels with different twist rates can definitely account for the 50fps difference..
 
My RTI external adjustable reg is also all over the place, worst of all is having to wait a long while (sometimes up to 7 minutes) to get it back to reasonable adjusted pressure (valve creep)

Regarding the difference in velocities, have you checked the spring you are using. I understand that there are 2 kinds. Stronger spring has 20 turns, normal has 22. Maybe you have the normal one ...

Just my thought
 
My RTI external adjustable reg is also all over the place, worst of all is having to wait a long while (sometimes up to 7 minutes) to get it back to reasonable adjusted pressure (valve creep)

Regarding the difference in velocities, have you checked the spring you are using. I understand that there are 2 kinds. Stronger spring has 20 turns, normal has 22. Maybe you have the normal one ...

Just my thought

Yes i got both, the normal and the heavier spring with less windings. 

Difference in velocity between the two isn't much, 10-15 fps tops. Extra hammerweight also only a couple of fps extra. 

I think the heavier spring plus extra hammerweight gained me 20 fps. 



I'm awaiting a Huma mini gauge which i will screw into the breech instead of the hose fitting, so i can rule out the regulator as the cause of all. 
 
All I can tell you is when I ditched the adjustable reg and went with a fixed straight fed reg, my Priest made big power. The adjustable reg is side fed. For some reason, even though its gauge would say 150b, my gun never responded well to hammer spring adjustments like it does with the fixed straight reg. Your gun essentially has a HP paintball reg. There is no need to wait for a reg tester. You make one using the same components a paintball guy uses. Cost about $30 and the Valve, bleeder and gauge are available on ebay. I just screw it onto my bottle, open the valve and see where my reg is set. Then I can add or subtract shims to get it where I need it. I can also let it sit and see if it creeps or release air with the bleeder and see how fast the reg recovers.
 
All I can tell you is when I ditched the adjustable reg and went with a fixed straight fed reg, my Priest made big power. The adjustable reg is side fed. For some reason, even though its gauge would say 150b, my gun never responded well to hammer spring adjustments like it does with the fixed straight reg. Your gun essentially has a HP paintball reg. There is no need to wait for a reg tester. You make one using the same components a paintball guy uses. Cost about $30 and the Valve, bleeder and gauge are available on ebay. I just screw it onto my bottle, open the valve and see where my reg is set. Then I can add or subtract shims to get it where I need it. I can also let it sit and see if it creeps or release air with the bleeder and see how fast the reg recovers.



It's not a reg tester i'm waiting for, just a cheap gauge. You can screw it under the breech and let it sit there instead of that hose fitting and read the true pressure of the reg. 
 
Got the Huma gauge in the breech now so i can read the true regulator pressure. The gauge on the reg itself shows around 6/7 bar more than the Huma gauge in the breech, so i could rise the pressure a little to get a true 150 bars. 

At 150 bar i now get 879fps with the 25gr Redesigned pellet. So it's better, but still a little short compared with Gregor in his review.



What are you guys getting at 150 bar with .22 JSB heavy and/or Redesigned? 

1574956226_4335471935ddfecc25bf779.61058349_20191128_162952.jpg

 
Hammer and trigger are a big problem in RTI 1 and 2,poorly done internal ballistics. Read more on GTA forum...

https://www.gatewaytoairguns.org/GTA/index.php?topic=159722.0

I would say that judging from your pictures, that gun has been through hell and had a few bad modifications. So, don’t be putting the gun down when your modifications/problems are caused by your fault.
 
Harold, I am shooting with 130 bar and the 18 gr JSBs are clocking around 930. Now, my rifle is a combination of the I and II, I front parts and II rear block and parts. I don’t use the hammer weight, but do use the heavier spring. I also have a custom butt plate that allows for no preload on the spring. I do believe that I have a little free flight to my hammer also.

You might try backing your reg down to around 125 bar and set your hammer spring as tight as you can, without creating a bunch of hammer bounce, and then start raising your reg pressure and see what you get between 125 and 150 bar.
 
Harold, I am shooting with 130 bar and the 18 gr JSBs are clocking around 930. Now, my rifle is a combination of the I and II, I front parts and II rear block and parts. I don’t use the hammer weight, but do use the heavier spring. I also have a custom butt plate that allows for no preload on the spring. I do believe that I have a little free flight to my hammer also.

You might try backing your reg down to around 125 bar and set your hammer spring as tight as you can, without creating a bunch of hammer bounce, and then start raising your reg pressure and see what you get between 125 and 150 bar.

Exactly the same as you. Took the extra hammerweight out, so only the heavier spring, and @130 bar i get 930's with the Heavy's.