Velocity loss with BNM breech

[Ken]

 I started with the kt2400, original velocities were approx 540-550 fps. I erased that string so going on memory. Got about 40 shots per cartridge.
I then installed the blue spring and the spacer from the 2300 series pistol. Averaged roughly 450 fps at an 80 shot count.
Installed BNM breech and velocities are approx 415. Fixed leak at breech seal from when I pressed pellets back instead of shooting them. On the other hand, when the bolt is inserted into the breech the o-ring will not hold it in place if I tip the pistol so the muzzle is up in the air. It has passed the tp test when I loaded a pellet and then removed the magazine to check.  When I install the piece that the transfer port fit into there isn't much pressure when I screw it down. Where should I look for air leaks?
How much velocity is lost because the barrel is inside the shroud? Does the insulation of the shroud affect the fps?
Almost forgot pics. Sorry no pictures of disassembly. Still learning. Can redo chrono tests if needed and give the rest of the numbers that don't mean anything to me yet.

[Trophyhunter49]

  Where should I look for air leaks?  Do the tissue test when you shoot it and watch where the tissue to swee where it moves or if you smoke blow a cloud of smoke around the breech and watch it !! I have several of the BNM setups on my guns and have really good ludk with them. No problems with any velocty , BUT I'm shooting HPA in mine.

[bgmcgee]

It's possible to lose a fewvfps just by design. The probe on the bnm breech is a little fatter than a good aftermarket probe. Also with the added length of the transfer port that could also cause a drop in speed. I still like mine regardless of the limitations.

[Trophyhunter49]

It's possible to lose a fewvfps just by design. The probe on the bnm breech is a little fatter than a good aftermarket probe. Also with the added length of the transfer port that could also cause a drop in speed. I still like mine regardless of the limitations.

  Me too!!

[Ken]

  Me too!!

+1
Out of curiosity, if I go the other direction and increase power instead of trying to conserve co2 will the fps loss be less? Has anyone tested this?

[Seatec]

How many shots do you get with a co2, I get about 38 before it drops.
Like mine great, just ordered 3 more mags, so have enough for a full co2.
What is the best for more power., power adjuster or modify the valve, or both.

Wayne