Jonathan - In agreeing with Ted; something to take into consideration when looking to maximize or increase shot velocity with an Independence is the inverse loss of shot count as the velocity goes up. I am going to speculate based upon my .22 Independence use and say with the factory hammer spring adjustment and the 850 ft/sec velocity, you get 3 to 4, match quality shots if the rifle is pumped up to 210-215 Bar and shot down to 150 Bar. Attempting to increase the velocity to near 900 ft/sec will seriously eat into this shot count due to the tiny 22cc pressure chamber. If you are OK with that, and/or more pumping in between shots - I say go for it. But I just thought I would point this out.
In no way am I questioning Ted's knowledge of shooting. In fact he kicked my butt in the second round of the Gun Slinger competition at the recent Pyramyd Cup (hi Ted!). However, I consistently shoot lighter weight JSB's at velocities well over 900 ft/sec in both my Independence and my Royale .22. The Royale shoots the 14.3gr JSB's at a little over 970 ft/sec and VERY accurate. Shooting the same pellets in my Independence at approximately 955 ft/sec also gives great results. Coincidentally, just two days ago I was shooting my Independence indoors at 15 yards. (It was snowing and cold outside) I had been enjoying the stress free shooting on the #1 power setting when I thought I would see the best group I could shoot using the JSB 14.3 gr at the #3 power setting of 955 ft/sec. I tethered the rifle to my regulated tank set to 160 Bar and shot two different magazine groups. The first 12 shot group was almost perfect, just barely larger than the diameter of the pellet itself. The second 12 shot group had two pellets that opened the hole up by about 20% or so, but still a very tight group. If was very difficult for me to concentrate that intensely through that many closely timed repetitive shots. But regardless, JSB 14.3's at well over 900 ft/sec are very accurate in my Independence. My Royale will post nearly the exact same results.
My Royale currently shoots the JSB 18.1 gr pellets in the 905 to 908 ft/sec range and again with very good accuracy results.
