Don you are using a pre 64 270 FW and IME these barrels were very good. But how much improvement you will see is hard to tell.
That said I have always gotten goo accuracy from the BBC bullets
so long asthe rifle scope combo was "good" and charges ran close to max. The BBC has a very heavy base and it seems it takes max charges to obturate the bullet into the rifling.
I don't shoot many groups with Bitterroots because I am so familiar with them and "know" they shoot. I have been using them since the 1980's in many calibers. Point is I work up a load with the Partition, sight in,and then do a "single shot, cold bore test" at 300-400 yards.
Usually that shot lands right in the same group as the Partition from my rifles and I am done.
On most hunts I take 30 Partitions and 10 BBC's. I use them interchangeably as the mood strikes me.
Thing about the BBC to remember....the faster you drive them, the faster the rotational velocity,the better they work.
On lung/shoulder shots at 300+ yards you likely will not find one recovered on anything elk sized on down. On a big mule deer at 300 yards, hold on the shoulder. Lung shots will kill him but a shoulder shot should drop him right there.
On any closer shots the higher impact velocity will cause more dramatic expansion and large frontal area. You will likely find them n the off side hide.
They are more bullet than needed for any deer and that load will easily kill elk,moose, and grizzly. But I get a kick out of using the original bonded bullet and they put the smack on big deer.