Freedom Arms recommends using magnum small rifle primers for the 454 Casull. They say it has better ignition in cold weather and also that it reduces the SD. I'm interested in the lower SD benefit. Could that be the same for any cartridge that is capable of using a magnum primer? I purchased a few cases of magnum pistol and rifle primers years ago thinking that they were required for certain powders. If they would give better consistency I will use them more often. Your thoughts?