Well here goes.
This pic shows three fireformed and annealed 257 Allen Magnums loaded with the 130 gr BCFBHP with a 25-06 round on either side for comparision.
This pic compares the 257 Allen Mag with the next hottest round, the 257 STW. The fireformed 257 AM holds 16% more powder them the 257 STW. Currently, the 257 AM is matching the performance of the STW with the 130 gr BCFBHP bullets when the 257 STW is fired out of a 28" 3 groove Lilja at 3340 fps.
The 257 AM is getting this same velocity out of a 25" A&B fireforming barrel. In past tests the STW proved to produce about 47 fps more velocity per inch of barrel length. This will at least be true for the larger AM so 3600 fps with a 30" barrel should be well within reach and with the proper powder burn rate, I am hoping for 3650 fps.
The 257 STW will top out at 3450 fps with this bullet in a 30" barrel.
This pic shows the shoulder detail of the two rounds. Even though the 257 AM is 0.100" shorter then the 257 STW, it holds much more powder by use of a fatter shorter case.