IMO, shooting a turkey at 300 yards doesn't require any skill other than with a pair of binoculars. While I prefer a rifle and would still use a .22-250 if the occasion warranted, a big part of the enjoyment of spring turkey is calling those toms in and watching them strut before you toast them at 25 yards or less.

.223 is proving a bit much for them in my experience, though. .22-250 even more so I'd suspect. Don't know about something in the range of the .221 Fireball, but have considered a .22 Hornet myself.