Nosler velocities are rather consistently....ah....optimistic.
.
Nosler data is shot with high quality, minimum spec barrels. What I've found is that when I use the data on my custom barrels with snug chambers it comes out real close to the real world velocity. As often as not I'll end up a grain less than their maximum charge to match their given speeds, and in some instances I've barely gotten off the starting load to match their top velocity.
When you take random factory rifles the results are mixed. Some will make speed, and some won't get within a mile of the book with their loads. Some won't make it with any load.
Mileage may vary.
Most everybody's pressure data is using quality pressure barrels.......Wiseman, Lija, etc.
I also have custom barrels, and Noz's data is still optimistic............I have 35+ years of chrono data in my binder--probably something approaching 15k rounds. Handloaders tend to "shoot" for published velocities and continue to pour powder in until they reach it, and then a lot of them seem to go further. Just look at some of the velocities being tossed out on the 'fire.
In the 90's a couple buddies and I had unlimited access to a Oehler M43 Ballistics Lab. We bought strain gauges by the dozen and glued them on a bunch of rifles. As mentioned before I have a 25" Douglas Premium bbl chambered in 270W. Velocities with factory loads were fast in that rifle, and within max pressures. With handloads I could do even better, in a few loads a lot better and still stay at max pressure. But that barrel is a definite exception.
