Bullboss .22 shot count numbers with reg ?

Ok ,I decided to lower my fps from 930fps using jsb 18.1 to about 870 fps with chp 14.3 but was unable to do so.The best I could get was starting at 900 fps and a slow fall all the way down to 600.I shot 110 shots from 200 bar to 50 bar with 50 usuable shots from. 900 to 800 fps but I just couldn't get it to hold a steady 870 give or take on the regulator no matter what I done adjusting the hammer spring.The shot string always started at about 910 ish with a slow fall all the way through.
im wondering if the regulator is bad?
I also noticed during my testing the jsb 18.1 would start at 930 fps and a slow fall to 900 for 20 shots ,it just never held a constant fps of say 930 through the shot string.
I'm going to pull the reg out this coming weekend and see what the shot string looks like then.
I was actually surprised to see 110 shots from 200bar to 50bar with 50 usuable at 30 yards just not a constant fps always slightly falling every shot..
Lol man I did alot of testing, shoebox for the win:)
Ooh the regulator is an air superiorty if that helps anything.
What do you guys think?
Thanks