I did see something at some website that the primer manufacturers will not comment on differences among various brands regarding ignition efficiency and what some mistakenly call "Hardness" (when they really mean firing pin impact sensitivity). From personal knowledge of what Winchester, Federal, and Remington do in the way of determining primer impact sensitivity for QC purposes, they all do almost exactly the same tests using an identical laboratory drop test. This involves placing a primed case (or something similar) in a fixture with a firing pin, then dropping a steel ball on the firing pin from various heights (called a "run-down" test) to determine a "critical height" (H-bar) which is the drop height of a specific ball (usually two ounces or four ounces, depending upon the primer type) which on average will produce a 50% probability of firing or not firing. Mathematical (actually statistical) calculations are performed to determine the "all fire" and "no fire" heights.

In the case of handgun cartridges, those using small primers usually have no-fire heights of around 1" and all-fire heights around 11". Those using large primers are around 2" and 16" respectively using a two ounce steel ball. What this really means is that H-bar for small pistol primers is a little less than that for large pistol primers (normally around 4.5" for small primers and 6" for large primers).