Just had a custom rifle built, 300 win. The speeds I am getting are slower than what was expected from the caliber and barrel length. It is accurate, but I have read the speed can increase after 100 rounds or so. Is this true? If so, how much? I have friends with the same builds, and they are getting faster speeds with less powder ( some 2g less with 50 fps more speed). I don't know enough about barrels/builds to understand these two anomalies. Can anyone explain?