Have you ever had a rifle that you knew you shouldn’t like or keep or put any money into but you did anyway because deep down you really loved it? That is the RPR 556 for me.
The fact that they cratered the shit out of primers and Ruger basically pulled the plug on them because they weren’t worth the hassle makes them that much cooler to me.
But in reality, it also offers a lot that other factory rifles simply don’t - good aftermarket support, the right twist and chamber for heavy bullets, full chassis modularity and adjustability, etc. Not to mention, I could buy like 4 of them for how much I have invested in my custom .223, it shoots the same as my custom, and since getting the bolt bushed it’s been 100% problem free. It’s one of those weird things that you probably wouldn’t recommend to someone just getting into it because there are better options available, but anyone that shoots it ends up wanting one.