Barrel cleaning and velocity changes?

[greenecj]

Like in another post I'm in the process of building a 280AI. New shaw barrel, so obviously ill have to do the break in process.
So here's my question, can I start load development during the break in process? Or will the cleaning of the barrel change my velocities?

 

[PddPdd]

I think most would agree that you can select your preferred bullet and start shooting it with your preferred powders to find your comfortable pressure limits for each combination. These limits will change some as you resize your brass from firing and as your barrel breaks in but it will save you some time later in down selecting a powder/bullet combination to go forward with. Remember to thoroughly clean your barrel between bullet changes.

 

[Mikecr]

I'd break in the barrel and fully fire form brass before beginning load development.