As most of you know I am a fledgling reloader. I'm still calling my experienced friends with stuff like " help!" and "Why is it doing this instead of that?" Etc etc. Recently I got a batch of Sierra brass, once fired cases. After attempting to reload them I realized they were meant to be used with small pistol primers instead of large ones. Never seen this before with 45acp. I ended up separating them and giving them away as it was easier than re-configuring my press just to reload a hundred or so cases. What would their reasoning be for this? Anyone know? Is there some advantage to this?