I think as much as anything it is down to having a pellet which is extremely predictable in my rifle. I have had the same in the past with both Air Arms and JSB, but have struggled to get really tight, really consistent groups that are predictable in the wind and these H&N's seem to be doing it for me.
Speaking to one of the top shots in SWEFTA today, he said he tried them a little while ago and found them no better than what he is using, so they are not a panacea to all ills.
I have also tried some RWS pellets in the same rifle, and found they perform ver poorly, yet Matt Hirst, who could out shoot me all day with his good eye closed has been doing very well with them.
Just nice to have an additional pellet to consider when setting up a rifle.
And on the subject of split skirts, I have just inspected another full tin and found three split skirts, and from what I can see under a lens, it looks like some sort of tooling mark, so I am going to get in touch with H&N and let them know, so they can take a look for themselves.
As for my scores, I think all future improvements will be entirely down to me. Of course any deterioration will be blamed on my rubbish pellets / scope / rifle.
"I'm your huckleberry, that's just my game"