Thread: What 6.5

There's a big outlay of money and range trips to move to a new cartridge:

Mag and feed fix up
Dies
Shell holder possibly
Small primers and tool (if you go that way)
New powder type
New projectile experimenting
If you can just drop in your previous powder, projectiles and primers then likely your new cartridge is pretty much the same as the previous one and why bother changing ?
Load work up with untold ladders, test batches, chronying, trips to the range, trajectory confirmation, terminal ballistics verification (goats), relearning wind and other behaviour.

Stuff you need anyway if you rebarrel in the same cartridge:
Barrel
New brass
New suppressor

People say the Creedmore is pretty good so you're not likely to improve on it unless you've got length to spare in the action (tikka).
You might be able to do minimal work up for a new load and if you can get one shooting to the same velocity and trajectory it will be an easy and good swapover.