Would the AccuBond bullets allow for more powder room or would their longer length impede on powder capacity for the 270 winchester as opposed to the Partition?
you will see a marginal loss in powder capacity due to the boattail. If you are shooting a compressed load this could be a problem. Back off 10% and work back up for your rifle. I doubt you will see a large difference in velocity at all.
In over thirty years of reloading the 270 I've never had a problem with compressing any loads. I have used the slower burning powders though, H-4831, H-1000 and r-l 22.
I would agree with the other guys, but there isn't a 150gr AccuBond in .270. The 140gr AccuBond is about the same length as the 150gr Partition though I would just suggest seating the bullet further out of the cartridge. That is of course assuming that your magazine will handle the length and that the bullet is not into the lands.
Thats too bad there isnt a 150grain AccuBond, so i am going to be using the 140 AccuBond with a longer seating depth. I chose the 140 as i will be using this a a deer / elk load for the 2006 season, will update when i have an accurate load developed.