Ok I did the deal with a 25-06' that had a collapsed neck . No sense messing up a good case . Expander out , I formed a 7×57 with a 25-06 neck sticking out of it like a MG blank . Annealed to excess with the deliberate intent of making it readily conform to all of the angles and edges .
My case length isn't an issue chamber gunk maybe but not the length , true length is 2.265 , the book calls 2.235 . The neck/shoulder jct is about .010 short but the shoulder/body is where it should be . The shoulder OD is .006 fat while the neck OD is dead on at .324 . The "blank" neck is .284 .
The form case was fired 2x with 12+ gr of Unique and settled grits topped with a gob of Darrs lube . The collapsed neck pushed out 90% flat the first time and all of the hard cam to close was removed . The necks and shoulders were polished with 0000 steel wool . Primed , loaded , and fired again rifling dents/marks show up with .212 smooth and step from neck to throat .050 long . The 25-06 case is 2.560 now . The neck fold is out and flat even the lube dents are gone . Nothing was sized for the second firing . I'm pretty sure 30k was enough to push stuff to full form . Long long Savage/Weatherby like straight leade requiring long long seating to reach the lands . About the only way to fix that would be to ream it 280 or face a .1 off the barrel , and buy a 7×57 reamer . I suppose a 180 and size the whole bullet.284 .
I might have enough room to just to just turn the barrel down 3 turns and conventionally finish ream the chamber .
I will figure something out I've shot several of these long throats successfully.
Size the .285 to .279 and roll them in paper , maybe .