About the .223rem and the 5.56 Nato?

I want to want grains you can get the rounds in all of them, what their distance, feet per second is, ibs of pressure, I also what to know like the types of jacket you can get them in and what their designed for? I got a new Mini 14 with ATI stock, I want to why it umm Tulammo 55 grain steel cases it has problems with and if I can fix so it can fire this casings or that my gun will only use br casings? Anyone have problems like this before? I also want a list of pro and cons of my rifle vs ar-15 or other versions of the m 16? thank you