I have decided my next barrel will be in another overbore 6mm round when my current one in 6mm Ackley is done. I don't have a lot invested into it brass-wise, so I'm not stuck with this caliber. My plan was to use a 30" barrel in order to achieve maximum velocity. Originally I planned on another 6mm Ackley, but the lack of good brass is disconcerting. My next thought was 6mm-284, because of good brass, but then 6mm-06 Ackley was spoke of, and it also has good brass, even cheaper. What can each round achieve with bullet weights of 100+ grains? I was hoping for 3300 fps from 115 grain DTACS from the 6mm-284, I was told the 6mm-06 Ackley is a little bit faster, maybe 3400 fps from Lapua brass? Does anyone have experience with these or a different fast 6mm?