There are more attractive alloys than "solid copper" to make bullets, thus addressing some of the concerns of the weight to volume (size) ratio. Famously, CheyTac mills solids, and the idea is hardly new. Over in Europe there are different companies (and individuals) producing solids, as lead is banned for hunters in several areas (most of Germany, I believe). Some are full of it, others reportedly produce outstanding components. I am eager to witness testing of solids based on a 'track-at-long range-design' that were made by a start-up, but have had pretty poor experiences with solids produced by LOS (a slovakian company). I shot those in .224 and they were awful. Better as caliber goes up (have seen acceptable groupings in .308) but apparantly it is bloody hard to produce consistent rounds by milling a solid material. Kind of has me wondering what the start-up will amount to, but as it's a friends' I am hoping for the best. From what I can tell you do need much more serious equipment than a table-top mill to consistently produce bullets to demanding specifications though.