Tone, maybe it is because the pellets are manufactured to work in the production rifles that are available to buy, not rifles that are taken to the extreme of what can be done if you try hard enough. You have clearly built a border line rifle which on the limit has become extremely pellet fussy.
To say the pellets are no good in that situation is like complaining your car doesn't achieve the manufacturers claimed mpg after you fitted twin 40's!
HFT, for people with only 2 buttucks!
VooDoo TwoTwo The next chapter.