1. I can't type what all to look for, but one thing you can check is, the button hinge pins on the action sides, should be "tight". You should NOT beable to turn them or move them

2. If the bbls were factory fitted, they would have the same ser. number... Very unlikely, as only a handful of ser. numbered sets were made, and they were cased with the ser. number stamped on the case too... They "could" have been fit by a dealer, gunsmith, or even Valmet USA, but there's no way to know that for sure.

3. Great mount, works very well, but it is a heavy mount! When used properly, they do come back to zero...