My experience is not far off of Tom's . I think it was 2018 at the IWA in Germany, the chief engineer at H&N gave me a tin to test. They were not on the market yet. I measured 100 for size and weight and visually inspected them. There were a couple that had light damage but only 4 that were not 9.6 gn and only 2 or 3 that weren't exactly the same head size , but these in both categories were 0.1 gn off and 0.01 mm off. EXTRAORDINARY consistency ! The only other domed pellets I've seen close to that were QYS. Those were actually only 4 of 100 that were 0.1 gn different but were ALL exactly the same size and no visible damage.
The shooting results weren't as good though. I tried them in about all rifles that would shoot them between 840 and 900. I don't remember a single rifle shooting them better than the JSB 10.3s. That's not saying they were bad, just not as good and blew a bit more in the wind, as well.
I would say they are worth trying... especially if the production version is as consistent as the ones I tested.
The QYS , by contrast, have shot better than anything in every rifle I have in proper power range. Similar to the FT's, they blow a bit more in the wind than the 10.3s.
Just my experience,
Bob