.177 Brocock Bantam on CA ground squirrels

I've been hesitant to use my .177 Bantam on ground squirrels here since most of my shots are between 50 and 100 yards, some out to 125, and very few in the 35 to 50 yard range. Well, yesterday was a fairly calm day, very light breezes and about 80 degrees at the area I hunt east of San Diego. I decided what the heck, and brought the Bantam. This is that time of year when all the young squirrels are coming out of their burrows, and haven't yet learned caution, so it was truly a banner day. I only shot for about two hours, and lost count after 15, probably topped out between 20 and 25. On just one field area I shot 6 in a row at one boulder at 46 yards, and another boulder at 77 yards I got 4. No photos, didn't want to take time to get them and by the time I did, only half were left as the Bobcat got a couple, and older squirrels dragged the bodies into their burrows for a snack... All of my shots were head shots, and I aimed high on the head since I didn't want to just injure a squirrel with a body or gut shot, and therefore I missed 9 or 10 shots high.

One thing I did notice was that with the lower FPE (shooting 10.3 JSB at 925 FPS), the head shots on the squirrels resulted in an immediate squirrel dance and helicopter tail. With the .30 FX Bobcat Mk2 head shot, the squirrel will be still for a few seconds, and then start the dance. Has anyone noticed that the time between head shot and dance varies with FPE of the hit? Big difference between 20 FPE at the muzzle and 80 FPE. 
;)