Had some wierd happenings lately with some .280Rem loads.
Firstly I fireformed some 30/06 brass and they came up real good, only shorter than the usual .280 Rem brass trim to length. I didn't have any .280 brass yet so I decided to just use these to work out some loads for when the .280 brass arrived. Anyway, I neck sized the fireformed brass and loaded some 139 Hornady Interbonds and SST's, both with 58gns RE19. Both loads shot great at 0.5" SST's and 0.65" Interbonds.
Then the new Remington unprimed .280 Rem brass turned up. I necksized the brass and chamfered the case mouths and duplicated the loads. They grouped into about 2"??? I thought fair enough as the 06 brass was fireformed to the rifles chamber. I went back and neck sized the now once fired brass and duplicated the loads again. Back to the range and again, groups around 2" or just a little less. I again tried the fireformed necksized 06 brass and the groups were good at 0.5". As far as I can see, the only difference in the brass is the neck length as both are now fireformed to my chamber. Will it hurt my rifle to keep fireing loads with short necks? Could there be any other reason for these findings? I think I will try again with the once fired .280 brass but just try neck sizing half of the neck instead and hope this works. Any other things I should/could try?