I wouldn't be fooling with backboring a barrel that may be chrome lined like many Berettas are. I would take a couple of ounces from the heavy stock and be happy. I have one lovely matched cased pair of 30" Evans game guns, both at six pounds, six ounces. I try to shoot more shells out of the one that came to me not broken in. When that one is broken in, it will be half of a true matched pair.