I was going to say to say the same as Dyno Dave, the FTP as with most other Air Arms rifles do not have a gland seal on the firing valve stem so some air escapes along it during the firing cycle. Quiet normal, but you would expect a groove and o ring in there to prevent this when you spend that much!
The story about the shroud back venting through the block is fantasy!
HFT, for people with only 2 buttucks!
VooDoo TwoTwo The next chapter.