The only AR I have is my Stag 2TL. Ever since I bought it this summer I have been looking around at what I want my next one to be. After reading here for a while, I have decided to build an AR. I want to supplement my 2TL with a varmint rifle. I plan on building the upper to start. I have recently started reading more and more about the .204 ruger. Does anyone have any experience with this round? Being new to the AR world, I was also wondering which parts are caliber specific.