Reloder 28,
I have gotten excellent accuracy from Partitions--but generally if they're seated very straightly. I suspect the reason the rear core section tends to "bend" a little more than many other bullets--but also tend to follow the general rules that long-time Nosler bullet designed Gail Root suggested years ago. He advised switching to a slightly faster-burning powder if Partitions didn't shoot like you hoped, because the faster powder would "bump up" the exposed rear core to fit the particular rifle's barrel better.
I have also found that maximum loads do basically the same thing. Have gotten excellent accuracy from Partitions in calibers from 6mm to .375 by pushing them harder. In fact the first big game rifle I ever got consistent 5-shot groups under an inch with any bullet was my grandmother's old Remington 722 .257 Roberts, way back in the 1980s, with an IMR4350 load that got 3250 fps with 100-grain Partitions. But there have been many other instances as well.
Thank you for this input. It makes sense given the bottom of the jacket is exposed. I will focus on the obturation aspect & certainly try some faster powders. My main focus is a favorite 280 Remington I have been tinkering with sporadically since 2008. I always felt a 150 Partition would be the ultimate combination in a 280.
I was ONCE able to get a 3/8" group with 150 PT's out of it using 7828, but it would never repeat.
