chronograph testing with JSB 18.13 Gr

As you all know, I installed a TT top hat in my high flow tank, but could not shoot with the first insert out, this would cause the gun to dump. So I installed a Condor .177 Cal valve spring which took care of this problem. Anyway I just got my order from Pyramyd air and in it were some JSB 18.13 Gr pellets so I decided to run some strings across the chronograph. Here are the results. The first 20 shot string was shot with the first insert in and a power setting #8 starting at 2900 PSI and ending at 2700 PSI. Shot #1 1001, #2 1017, #3 1018, #4 1018, #5 1015, #6 1016, #7 1020, #8 1014, #91017, #10 1015, #11 1012, #12 1015, #13 1012, #14 1014, #15 1012, #16 1014, #17 1010, #18 1009, # 19 1010, #20 1004. I now started a second 20 shot string with the same starting PSI and pellet only I used power setting #4 Shot #1 956.4, #2 959.5, #3 957.0, #4 965.0, #5 971.5, #6 972.8, #7 976.7, #8 975.8, #9 970.1, #10 980.5, #11 981.3, #12 985.5, #13 981.3 #14 987.4, #15 984.3, #16 988.1, # 17 983.1, #18 990.9, #19 983.4, #20 986.9. I think these will shoot good on power setting #2 with this first insert. Now I think I will try a 30 shot string only now I will use the smallest insert for the TT top hat and used power setting #10 Shot #1 895.2, #2 892.9, #3 889.0, #4 894.8, #5 898.5, #6 897.9, #7 895.5, #8 903.2, #9 897.5, #10 896.4, #11 898.7, #12 898.3, #13 899.5, #14 902.1, #15 900.0, #16 896.0, #17 896.0, #18 896.1, #19 896.5, #20 899.4, #21 902.5, #22 902.0, #23 895.3, #24 899.1, #25 901.5, #26 897.8, #27 896.5, #28 892.9, #29 894.3, #30 895.6, I think I could get another 10 shots at least. I have been told that these pellets are the most accurate at this speed so I guess I will try them at this speed or if anyone can tell me that there is a better velocity for these pellets then please let me know.