Preface-I don't have any dircet knowledge of how Bergara tolerances their actions, any assembly should be checked for proper headspace before use.
I have a feeling we'll find out soon enough that they are capable of using prefits. There's another thread on here somewhere where someone had purchased a premier action bolt to go into his HMR. Bergara sold him the bolt and said it would drop right in. If that's all true it stands to reason that at the very least their bolt heads are held to an interchangeable dimension, at that point they may as well do the same for barrel and receiver. Also it would make it easier on them to produce. Much more straight forward to machine thread and chamber all in one go to a specific dimension than it is to do multiple separate op's and hand fit each action they produce. All assuming they have modern turning centers capable of the tolerances, which I'm assuming they do. Just a matter of doing some QC and potential adjustments before it comes off the machine.