I have shot them in a BSA Lonestar at 920 FPS. That is way beyond their 25J rating since it works out to around 50J. It's basically a pellet for springers, not PCP airguns. Accuracy was bad, and pellet skirts were deformed in pellets I recovered from water targets.
Thanks Beezer i guess i should skip them and look for something else in 25 gr or about there.
My Taipan doesn't like 25gr Jsb very much but it likes 26gr Hades out to 60 yards.Only problem is they are terrible in the wind.Even slightest breeze pushes them away from target.
Regards Marko