This may help.
8mm Rem Mag case necked to 338 that has been fire formed. This gives you a 10 thousandths case taper & a 38 degree shoulder
250gr HPBT Sierra
The top left target was some 416 Rem Mag brass I was fireforming with 225 Hornady Interlocks. 85gr IMR 7828 & CCI 250 primers. 2967 FPS (Low), 2995 FPS (High). I also notice that that target should have been rotated 90 degrees CCW as that is how it was at the range.
The top right target was the last 3 rounds left from my 1st 338 Gaillard that I had. They were loaded with 250 Sierra HPBT, 340 Fire Formed Norma cases 89.5gr RL25 and CCI 250 primers.
2887FPS (Low), 2959FPS (High).
The lower left target is a 5 shot group of Barnes 225gr XXX. These were Fire Formed 8mm Rem Mag cases with 86gr IMR 7828 and CCI 250 primers. 3054 (Low), 3077 (High).
The lower right target was an experiment. 200gr Nosler Ballistic tips with Fire Formed 8mm Rem Mag cases with 88gr RL22 and CCI 250 primers. Nosler does not make a ballistic tip in 200gr anymore, only the Accubond. I figured I'd try these before I used my Accubonds. I must say I was impressed!
3249FPS (Low), 3271FPS (High).