I have nearly finished the 6mm AR15 rifle based on a Davidson Defense upper. I have a Vortex Strike Eagle for this one. But now, the hard part. 6mm Arc ammo is about as scarce as a hen's teeth. So I bought the tools to convert some of my Grendel cases to 6mm Arc. The process doesn't sound too complex, but apparently, the case neck ends up too long after the reforming. So I bought the Lee trimmer and die to get that job done. I think the Grendel cases I have take a small rifle primer, and I have plenty of 6mm bullets, so I have to get busy this weekend knocking a few out so I can take this rifle to the range soon. There are loads on the web to use as a starting point depending on my bullet selection.