fellas,

wondering what is needed if any to get a RN to feed in my action "if" I choose to rebarrel to the .458WM I've had the rails worked and feeding "timed" perfectly if you will for the prior .338 belt. Had a smith mention that a feeding problem could arise. any truth to this?

Yes, it may not feed the .458 as the bullets are a whole lot more "blunt" than .338 bullets. Only way to tell is to try it.