a friend of mine is a master-degreed custom rifle maker, who made a number of doubles in .450 NE and .500 NE´s over the years....
last year he made two .450 NE rifles with an experimentically short twist of 1-10" in custom-made-barrels instead of the usual twist-length (1-16"/1-18").
He made a lot of penetration tests on test-mediums that showed substantially better results than the rifles with standard-twisted barrels.
Bullet weights of 480 to 600 grs were no problem to shoot with good accuracy, bullets under 480 grs were somewhat finicky....
The two guys that are owning that rifles came back from africa, hunting buffalo and elephant: ALL bullets (elephant: 2 w/frontal brain shots FMJ Woodleigh 480 grs, 2 with diagonally body-shots FMJ Hornady 500 grs, buffalo: 3 w/frontal brain shots FMJ Woodleigh 480 grs, 2 w/body shots RNSP Hornady 500 grs) exited completely!!
The hunters (that are no newcomers in hunting african game) as well as their PH´s were absolutely delighted from that results!
the velocity of the hunting rounds (measured here in european sumnmer) was 2.090 to 2.160 fts....
I wouldn´t wonder if with such a rifle-twist the .458 Win mag wouldn´t to the same and though play a totally different role...
Testing .470 NE barrels with a shorter twist didn´t give acceptable accuracy at all, so that experiment ended before making a double in .470.....
Next project may be the .500 NE cartridge with a short twist.....