Why not chamber it in .244 Rem (6mm Rem) and make cases from 7x57? If somebody fires one in a 7x57 chamber, no harm done. If you try to stuff an unaltered 7x57 in the .244 chamber, bolt won't close. Mark barrel "6x57 Krag Special" or some such fiction.

Should feed better than stubby .243 Win. anyway. Plenty of die sets, reamers, gauges available.