I simply cannot recall all the .458's I have owned or used. Never ever, did one not produce sub MOA performance and half MOA performance is simply nothing to brag about as it is relatively common with this caliber.
Can you share your loads with cast and lighter bullets in the 458 that produced such accuracy ?
Nope.
Never shot a cast bullet and never claimed to either.
I have however, shot from 300 to 600 grain bullet weights in the .458's.
