An accumulation of facts and effects observed during twenty five years and over 700 Miller Number Tests by White Rock Engineering using the procedure in ASTM G75-89 Test Method for Determination of Slurry Abrasivity (Miller Number) is presented. Included is a discussion of 33 factors that could affect the Slurry Abrasivity Test results and how influential they may be. Probably the most surprising anomaly was the discovery that particle size of segregated sand samples do not always exhibit the rule that fine or small particles are less abrasive. The description of an accepted shortened test time and a newly designed specimen holder which can be applied on older machines is included.