opinions on this shot string.

[SuburbanMe]

Mrod .22 H&N FTT 14.66g

30 shot string

978
957
956
957
956
947
894
951
936

941
931
927
921
907
912
863
898
899
894

890
871
773
863
851
645
835
822
811
812

End string.

[wilsonj1018]

It's pretty horrible, try backing off you're hammer spring tension around 3 turns, turn the restrictor in the side all the way in and back it off 2.5 turns and see what happens

[SuburbanMe]

I'm running the Bstaley mod, so velocity remains all the way open.
Also, spring is all the way out.

[wilsonj1018]

You need to decrease the hammer length in that case, and possibly find a weaker hammer spring.

[nervoustrigger]

Agreed, a constantly decreasing string indicates that you need to back off the hammer (or fill to a higher starting pressure if it is safe).
 
In terms of the bstaley mod, do you have a baseline shot string with no O-rings installed?  Sorry if this is a rudimentary question but the best results (long, flat shot string) will be obtained by targeting an energy level that is somewhat lower than the max power you get with no O-rings.  Say, taking a string that peaks at 35 fpe and tuning it for 30fpe or 25fpe or perhaps even lower.
 
I find it helpful to locate the point where the shot string is just barely being affected by the stack, and then increase the stack height (or back out the hammer's nose, if adjustable) to the point where there's a substantial de-tune so as to get a grasp of how the system is responding.  Say, taking it down from a 35fpe peak to maybe half that.  In many cases, that will only require a change of 0.05" or so.  If the nose isn't adjustable, a flat washer added somewhere in the stack works well for this.  Then by looking at those extremes, it gives me some clues about how to proceed.
 
To use an example, I just finished a bstaley on a .22 cal FD PCP.  Bob had managed 18 shots at 20fpe and to me that seemed like a great tune for a lightweight squirrel gun so that was my target.  I had done some porting and it was cranking out 40fpe with heavy pellets on 1500psi.  The soft seal on the factory poppet had blown out and I went back with a hard Delrin one, which turned out to complicate things just a bit.  It made it super easy to open the valve even with the power adjuster all the way out.  I tried various O-ring durometers and stack heights but could not get a decent string.  A stack too short or too supple didn't reduce energy enough and allowed very obvious audible hammer bounce, but by the time I had the stack tall enough or stiff enough to reduce the energy, the string was really short.
 
So I cut off a couple of coils, shortening the spring from 2.3" to 2.0" long and tried again.  That made the spring so short that it didn't reach the seat on the power adjuster so I figured I'd end up needing to order a weaker spring or grind some weight off the hammer.  But I turned in the power adjuster 4 turns which basically just took up the slack (no actual preload), and with an O-ring stack of two (2) 70D and one (1) 90D I got the 18 shots at 20fpe.
 
Good luck with your tune and keep us posted.  I've gotten spoiled with the simplicity of tuning regulated rifles and I'm still working on getting comfortable with bstaley tunes so my ability to help will be somewhat limited but there are a lot of talented folks here who can help.