When all else fails, replace the hammer spring?

[darryl]

Some of you may be aware of the trials and tribulations of a few owners of the Hammerli Pneuma Elite 10 (over in the Turkish Gate). I've been trying to get mine on an even keel and came to learn, with the help of others here, to suspect the trigger adjustment. I was getting two distinct POIs within a 10-shot magazine. I've since cured that problem, but my strings show another problem. There are inconsistent variances in the FPS. While the string looks generally progressive, the "bow" is not a smooth one. That is to say I may see, for example a shot string like this:
920.6
895.2
905.5
925.8
900.1
933.0
910.0
908.0
939.8
922.9
I have adjusted the 1st and 2nd stages plus the pull weight, and got these  following results once the pressure in the air tank dropped to 100 bar (took 9 shots from 100 bar dwon to 90 bar):
888.3
871.7
868.1
862.3
853.6
845.5
839.9
834.1
823.8
{please see next post to continue}

[darryl]

As you can see in these two strings from the same fill (190 bar down to 90 bar) the variance in FPS is more even in the 2nd string, and more widely varied in the first string. So I'm guessing the hammer spring is weakened and cannot open the valve with any consistent results until the pressure in the tank dropped to 100 bar (see the 2nd string). So within the effective ability of the (weakened) hammer spring a consistent drop in FPS can be seen. Again, I'm guessing the hammer spring is fatigued. My guess is based on previous results which showed the variance to be more evenly distributed from the first string to the last.
I'm open to any opinions, and I can email copies of my latest xls spread sheet to anyone who wants to view them.
thank you,
Darryl
PS the wider variations of FPS showed in producing two separate POIs within a 10-shot magazine. That made sense to me. The smoother the "bow" and lower the the variance (Sd) the better the POI grouping until  there was only one discernible hole instead of two separate ones.