In order to establish bullet jump, for a number of years, I have been dutifully using the O.A.L. gauge to determine distance to the lands. To establish confidence in my results, I make make repeated measurements (10) and consider the average as the "true" value. In addition I have used other measurement techniques for comparison which should yield the same value. My frustration is that results are all over the map. As a recent example with my new unfired 22-250 Shilen Match, the maximum and minimum measurements of one set (10) were 1.988" and 1.944" with an average of 1.967" which is typical of my experience with the O.A. L. gauge! I also used a separate technique which involved reaming the neck of an unfired Lapua case until the bullet could easily slip in and out, and then chambering it with some threadlock to permanently attach the bullet to the case while it was in firing position. The result of this measurement was 2.080"! In the many Youtube demonstrations of the O.A.L approach, magazine and book articles and forums I have never seen this issue of inconsistent measurements mentioned. It seems that one measurement is sufficient. My question is why am I getting such a spread in what should be identical results? Any suggestions would be greatly appreciated.