so far i have built 2 "ghost" guns from milling the 80% lowers on up. One in .300blk, and the other in 6.5 Grendel. I love both for different aspects. the .300blk because at under 100yds it packs a punch and is accurate, the 6.5 grendel because i can still hit a sub MOA group at 800yds so far... i plan on building a .458 socom and a .500 on the AR15 platform, and several on the AR10 platform. i love the gunsmithing hobby, it is an expensive hobby though. thank you for your comment.