I have an FX Independence in .22 the last 7 years. No problems with leaking seals whatsoever. At full power it recharges with 3-4 strokes for each shot. You get 7-8 consecutive shots without notisable shift in POI. At lowest power setting you need only one stroke for each shot to replenish the small reservoir. I am pretty sure it delivers more than 600fps but if you wait until tomorrow I will post a video for you shooting though the chrony.
Is there a single pump pneumatic out there that will do 600FPS in .22? I think Daisy has the Avanti or something like that name.I was thinking that would be about perfect.
Sorry for the delay in response. Had death in Mom's family and I had to go out of town.I watched all I could see on the Independence couple years ago but it didn't really appeal to me.I was thinking that a single pump hunting rifle would be good for several reasons. No recoil, no worry about temperature, no need for compressor or pump, no scuba tank, no buddy bottle, no sensitivity to hold like springer, consistent shots for a few.
A single stroke pneumatic may be really appealing, but since they don't make what your looking for you may want to look for a good multi stroke pneumatic such as an old Sheridan streak or new Benjamin 392. They have all of the benefits minus ultra quick follow up shots.
... single pump [.22, 600 fps] hunting rifle