I had done considerable testing with various full power 30-30 and 45-70 loads and cast bullet 5744 loads in lever-action and single-shot rifles, along with a modicum of testing of blackpowder and 5744 loads in various single-shot rifle chamberings such as the 44-90 Straight. In the full-power loads in the lever rifles, I had used the CCI-300 and had discovered superior accuracy to that produced by any rifle primer! I had tested loads with these primers for two reasons: first, the shorter cup provided added safety against possible magazine chain-fire during recoil; second, the softer cup seemed likely to provide more uniform response to the typically mild striker energy typical of such rifles. (This fact was considered in one of my earliest published articles, Handloader's Digest, where I described MOA loads developed for my Marlin 45-70.) In blackpowder and 5744 testing, I had seen very good results with the Remington 2½, which I had guessed might offer superior performance because it is claimed by those who engineered it to have the lowest brisance and highest heat content of any Large Pistol primer. I had not been disappointed.
Based upon decades of experience with magnum revolvers, I well knew that the primer blast can move the bullet and that propellant granules do not ignite instantly (a physical impossibility). One can examine myriad internal ballistics results to demonstrate the validity of these points but a few should suffice here.