The other problem with some older Speer (and some other manufacturers' data) is they did the load work-up in a pressure barrel, with pretty closely controlled SAAMI chamber and bore dimensions. Then they chronographed the pressure-developed loads in a factory rifle, which in at least one manual Speer claimed was done in order to show "typical" sporter velocities.
The problem with this is mass-produced rifles tend to have varying chamber/bore dimensions, which of course results in wider velocity variations. In one Speer manual this "technique" resulted in higher velocities from the .308 Winchester than the .30-06, the reason they added an explanation for the anomaly.
Luckily, most manual data these days, both pressure and velocity, comes from the same pressure barrel.
