I have a .38-40 rifle and revolver. I wish to handload a round that is compatible in each. From what I have read, it seems to me that the difference between a rifle and pistol primer is that it takes less force to detonate a pistol primer than a rifle primer. I am surmising that there may be greater pressures generated with a rifle primer than a pistol primer, but is this true, or not? And, even if it takes more force to detonate a rifle primer than a pistol primer, why would this matter? I cannot think of any time I would pull the trigger on a rifle and NOT want the round to discharge, so why would it matter if it takes more or less force to detonate it? So, I guess my question is two-fold: Why is there a distinction between pistol and rifle primers (in that if rifle primers do not always detonate in a pistol, why are not all tolerances that which are found within pistol primers?); and, should I still handload identical loads, compatible with my revolver and rifle, EXCEPT for different primers, OR can I reload using pistol primers for both? Incidentally, when I first started handloading, I did NOT realize there was a difference between pistol and rifle primers and I loaded, and fired, 100 .41 Long Colt rounds in a Colt 1895 revolver and had NO problems whatsoever. It was only after I fired all 100 rounds, I discovered there was a distinction between the two types of primers. Lastly, for those more technically oriented, what is in a rifle primer that makes it inherently different from a pistol primer?