Yes the problems you are having appears to be the same as the rest of us are having !
These variations do not really bother the average "Joe" who wants to knock off the occaisional rat or vermin of some kind and may buy a tin of pellets every couple of months or so, but field target shooters need a consistant quality (hopefully good quality) pellet that is predictable time after time and batch to batch.
Not wishing to be offensive to any shooter who does not do field target the same as I do, but enjoys some other type of shooting. more power to your elbow. It would not do for us all to be the same, but it would help considerably if the pellets were !!