Only just seen this thread but now everything makes perfect sense to me.
I had to go out and buy another load of lead last last year & immediately noticed that the depressions (not probable technical term) inside the pellets was larger than my old batch. I tried a few different sources and all the new supplies coming in seemed to have this new design. Poor scores followed and after a particularly bad round at the club I sat down on the zero range I sat down with tins of new Daystate Rangemaster, AA Diablo & JSB exacts all of which look and weigh identical. At 55 yards I was lucky to get a 10 shot spread from any of them within a 40mm kill area. Frantic, I opened a tin of old Daystate 4.52's from the batch I was shooting in 2004, when I won the worlds - 6 shots, straight from the tin, off the knee and through a hole no bigger than my little finger nail! I couldn't believe it.
That weekend Dave 'the friendly mountain' Croucher & I shot the BFTA Showdown with a busted up tin of old Air Arms Dave had picked up in some 'job-lot' sell off years ago for a couple of quid. Most of the pellets we shot had hexagonal skirts and you could see light past several edges when you stuck em in the breach - we both got to the quarter finals, with me clearing 3 courses in the process.
But now it all makes (Marketing) sense and we'll now be paying a premium for what used to be average performance....