Looking to purchase a Charter Arms 45 ACP Pitbull. I reload 9's and 38 Spcl for plinking. I always have small pistol primers on hand. But it looks like there will be 2 options in purchasing once fired range brass for the 45. Why did the case manufacturers develop the 2 primer sizes for brass? Is one better than the other? Any personal preferences? Since I load 9's and 38's, having one primer size on hand makes it easier. Any thoughts?