I was chuckling to myself that they took the rifle out with the white glove treatment and then take a steel caliper to it.
At gun shows, the occasion to take some measurements off of some nice rifles arises and it is always with plastic vernier calipers which give accurate enough measurements for this type of thing.

Great rifle though and as a "tribute" gun I don't think the intent was to make a direct copy. It sure raised a lot of money though which definitely WAS the intent so, a job damn well done to Rigby!