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?
You will run into the point of diminshing returns very quickly with a 6mm and 115s. I just have not found a 115gr bullet that will handle the velocities you are wanting. I built a 6-284, it would smoke em....literally. 115gr bullets through the target sideways and bent 90 degrees. Looked like boomerang holes through my target. It did this with d-tacs and bergers.
About 3200 with a 7.5 twist is the limit IMO that the current easily obtainable bullets out there can be pushed with any reliability.
I admit that I know just enough to be dangerous.....but dangerous at ever extending distances.
The 240 Gibbs is a very fast and accurate 6mm. It is all you can get out of a blown out '06 case. I have four in various configurations for hunting and targets. The two tight neck target rifles will shoot 1/2"-3/4" groups at 300 yards. I tried one off the JRS design which is all you can get out of a blown out 280 case. This holds a little more powder with the longer case but no significant velocity gain. The blown out '06 case seems to be about where the 6mm will max out. Anything larger than that just not much gain.
Predictions are difficult, especially when they involve the future
LTLR, i think you mentioned 3600 with 105's, i assume Sierra's. what twist/barrel length/powder combo do you have for this. i'm thinking an 8.5 twist would be about perfect for a 6/06 and the 105-107 bullets.