I've found them to be reasonably close. Most of the testing labs have high dollar equipment for measuring all the data where we usually have okay stuff so there of course will be variances. Not to mention the actual shooting equipment they use to test pressures and speeds. Rarely will you find exact speeds but you will find relatively close "in the same ball park" speeds. Or at least I have. About the only one I found some pretty high differences in was my Speer manual, I think it was #13, where I found some pretty major speed differences in both my 7mm-08 loads and my .300WM loads. Speeds weren't even on the same block as the ball park. The 7mm-08 load was almost 120fps faster than the published and the .300WM was over 100fps slower. Now this was back in 2005 or so and they may have been some powder differences or something.