lately, I've been thinking too much as usual <g>! As much as I like the idea of a 6.5x57 AI with 140 grain bullets (2900fps), I think there's more to the equation. Perhaps a .257AI necked up to 6.5, but reamed three millimeters deeper at the shoulder for a total length of 60mm. I honestly believe I could get 6.5-06AI ballistics in a case that would fit inside a standard mag well with a high B/C bullet, and yet not push it way back into the case. I think 3050fps is doable. Dies could be made by simply shortening a basic 6.5-06AI sizer, and running the reamer into a .260 seater. There are really three different 6.5x57 rounds. One is just the basic Mauser 6.5x57. The other is the .257x57 necked up (very slightly different). Then there is the 7mmx57 necked down to 6.5. I like the last one best even though the case capacity is slightly less than the others.
gary