Help, starting load for a 6.5/7 PRC

Is it a short barrel? I'm worried about keeping those projectiles together from a 26inch barrel with a conventional 6.5. Or have they got better?

Sounds like the cartridge people were actually expecting, should see good velocities, guessing 2225/Retumbo should be better with the additional capacity or even 2218/the 50BMG type powders come good.
 
Rifle is completed. ran a ladder with H-1000 64.5 to 66.2 . 65.8 and 66.2 seemed to be a flat spot with a 2935 fps average, both loads produced a group in the high .3's. going to run 66.0 till barrel speeds up, then continue load development.