Why do SXS barrel bore diamiters vary?

[Dean Romig]

Originally Posted by Mark Ouellette

Chances are that the balance would not noticably change.
Mark

And if Parker Bros bored a barrel oversize or back bored it and the gun no longer balanced and felt as it should, I'm pretty sure they would have invisibly remedied the situation. Of course we can't say as much for an aftermarket back boring job by someone other than the factory.

[Bill Murphy]

When gun shopping, I would rather be equipped with a bore micrometer than a scale. A smallbore Parker with .010 variation in bore diameter from left to right has been screwed with, end of story.