"It's (.257-.22-250) has been done."
The fact that it's "been done" was sorta the point, you know? The .22-250 is a necked down .250-3000 Savage, a .257x22-250 is simply a return to the parent cartridge. We have plenty of dies, cases and chamber reamers for that one!!!
What accuracy will be lost by necking up a .22-250 to .243? Last I heard, it will add .178" to groups.
How finicky is it to load for? Last I heard, it will take 27% more tries to find the best shooting load.
If you doubt those figures I'd challenge anyone to prove me wrong.
