In the Lyman data there are a couple of possible reasons the Ruger data is faster. First of all, I'd caution that reading any chronograph data as absolute is risky. You need to take into account the spread in the data and look at the statistical results. The only absolute you can count on is to take the data spread value for the Ruger and subtract it from the Ruger average, then take the data spread value for the Walker and add it to the average for that gun, and then comparing those numbers; you can then say the Ruger is X fps OR MORE faster than the Walker.