You'd be better off addressing this question in a bench rest forum, where this kind of precision is needed. In FT so long as you hit the paddle the target goes down and that is all you want. In bench rest you are trying to hit a pin head at 20 yards or so, and a deviation of just 2 mm will give you a 9 not a 10. That's when pellet and barrel consistency matters to the degree you're talking about.
FT requires a skill set which I think is unmatched in any other shooting discipline, which is why I enjoy it. And I don't weigh my pellets any more; I spent plenty of fruitless hours doing that until I realised that making mistakes with the wind plays far more havoc with your scores.