Talon SS Shot String

Just got a valve mod (home done per post here) finished and here’s the first string. Comments/suggestions please.

12″ barrel.

Crossman Premier pellets sorted and weighed at 14.2 grains.

Fill to 3000 psi pressure remaining-~2700 psi.

Top hat at 0.070 Power wheel at 6 to start

1-915 f/s
2-915
3-915
4-919
5-915
6=918
7-918.5
8-919
9-913
10-914
11-909
12-913
13-910
14-011
15-909

Average velocity=914.2 Energy=26.3 ft lbs
Extreme spread=10.56 f/s SD=3.46

Moved the power wheel to 8
16-911
17-908
18-908
19-907
20-902
21-901
22-899
23-897
24-881 PW at 4 (just to see what happens)
25-882

Average velocity=899.6 f/s Energy=25.5 ft lbs
Extreme Spread=30.16 f/s SD=10.48

Now, a question. Does it seem that the velocity os dropping off rather fast? I would expect more than 15 shots before the velocity dropped that rapidly. TH adjustment? Anything else? If these data are within expected performance, they will do what I want (vermin) but I’ll need to work on accuracy. The shots were all over the place, two to three inches at 35 yards. Grouped OK, well under an inch, until the velocity started to drop. Maybe switch to JSB’s.

Thanks for any comments/suggestions.

Abe