Years ago there was a 243Win and a 6mm Rem. I can remember when they were introduced. 243 sort of won. Then i saw a 6BR. I thought it was strange. And now there is a different flavor of 6mm/243 for everyday of the week and more, between the 6BR and 243. Can some one give me a quick summary of the various rounds and a description of their design. I have never owned one but am now thinking of getting or building a 6 mm for paper punching and varmints. I have available a either a long or short action. I can reload, form reform brass and like to tinker.