There is a lot of truth in the variations of gun, powder, primer etc. Also, I read somewhere that Vihtavouri uses all 26" barrels for their load testing which inflates velocities in relation to what a reloader would get. Let's face it, most 30/06 based cartridges are shot out of 22" barrels. Why in God's name would a reloading manual use a 26" barrel? So unsuspecting buyers of powder would think that Vihtavouri's offerings would out pace more popular brands? It's fine powder on it's own, they really don't need the hype.

I believe that most commercial pressure barrels are made 26" because that gives them higher pressure than sporter barrels. So that gives them a slight "safety" factor when they reach pressure limits.

Speer is a little more honest. They tell you that velocities were achieved with a 26" pressure barrel, and sporters should expect 100-150 fps less.

There is to be expected a reasonable amount of variation from any manual. Ive found that most manuals will give a pretty good ball park figure (honest figure), but if you expect like velocities from any rifle then you are most assuredly in for a dissapointment, the biggest cause of deviation from reputable manuals is due to the rifle. I like Speer, Hornady, Lyman and Nosler for getting worth while data. It is also my opinion that the worst compiliation of lies and utter BS is from Barnes.

You bring up a good point with Barnes Data.
I forget the exact reason for it, however because their bullets are solid copper, it screws with velocities and pressures and the like.
Be Warned: Do not use Barnes Data to load with normal copper and lead bullets. In a worst case, you could do some serious damage to your gun and yourself, and no amount of fps is worth bodily harm.

-Spencer