Ridge Runner,

According to the information I can find, the SAAMI max operating pressure spec for .25-06 is 63Kpsi also.

The only thing I can think of is that the velocity "data" used in the ad hype for the .25WSSM vs. the .25-06, and the claim of it's ability of the former to equal the latter, is that they knee-capped the .25-06 by shooting it in a shorter than optimum or typical barrel (22" or less) and shot the .25WSSM in a somewhat longer than typical barrel (24"+). That would easily account for the inability of the .25-06 to beat out the .25WSSM. But the truth is that most (but not all) manufacturers offer the .25-06 with a 24" barrel to take advantage of the larger case capacity and current slower burning powders, while the .25WSSM is usually offered in compact ultra-lite short barreled rifles.

The .25-06 is faster than the .25WSSM by a significant margin. I'd challenge anyone to show chronograph data from two rifles with equal length barrels and identical bullets and near MAX loads that shows the .25WSSM coming even within 100fps of the .25-06.

Mike