250 mm barrel left oem hammer spring .
Used black plenum spacer the 449 did occur at the end of the string around 100 bar .
First time I ever tuned any pcp so not sure about the 95 percent at velocity peak ? Not sure what that means still trying to learn.
What reg pressure should I have used ?
Should I put the weaker hammer spring in?
I'm not married to 17 fpe i just want 12 or above I mostly pest with this usually within 30 yards sometimes I do go past but thats rarely. I'm More focused on Accuracy I shot it some at 17 fpe and I was able to nearly stack pellets at 20 yards
But I have 1 of each barrel .177 .22 and .25 so I might want to switch around depending wear I'm hunting but I am partial to .25 the most.
Sorry, I did not do a good job of explaining that. The only reason you would need to change reg pressures between calibers is if you wanted to stay at the same power level and keep the hammer spring tuned 95% or so of the first velocity peak.
To explain this take a look at this snippet of Jack.K's tuning chart. Don't worry about the reg setting as that was specific to the caliber, barrel length and pellet that he was using. It's just the concept here that matters.
Each number under HST is a click counter clockwise from zero. At clicks 6, 7 & 8 there is no significant increase in FPS so 782 is the first velocity peak for this regulator setting. From there the HST is turned back down to five clicks, which is 97% of the first velocity peak.
At 97% or so of that first velocity peak one tends to get less energy spread and can take a shot or two off the regulator with no velocity spikes..
I would start over with your HST at zero and then see what your first velocity peak is.
I would be curious to hear what your velocity peak is in 25 with and without the black plenum spacer. But if you're happy with the results then don't bother.
I wouldn't worry about the hammer spring just yet.
One of my favorite things about the Leshiy is the ability to adjust power with just barrel swaps. No de-gassing, putting stress on o-rings, etc.
If you want to be above 12 FPE in 177/250 you might need it tuned a bit hotter in 25 than you have it now. But I haven't tried that with the plenum spacer installed so I'm not certain about that.