Well, I'll put this here because my Remington M700 Safari is stock - 26" barrel, U-notch & bead front sights, nearly new condition, just as I bought it off the used-gun rack back in 1967, at a really good price because it kicks! Somebody thought they needed a .458 Mag., fairly new caliber then, and shot half a box or so of factory thumpers. Then it was my turn - I loaded some factory jacketed equivalent loads (in the 65 gr. powder charge range), which are bearable offhand but not from the bench. I really was interested to see what cast bullets would do, envisioning a modern version of the .45-120 sharps. I discovered a number of things.
1) The ball seat is very long for the 500 gr. jacketed bullets, which permits the cast bullets to be seated out quite far.
2) Undersize noses are not good - example is the 457125 Lyman bullet.
3) A wad helps with a plain-base bullet. My all-around load was the Lyman 457121 475 gr. (seven lube grooves) crimped in the second groove from the bottom, 40.5 gr. 4198, and a toilet-paper wad - one square, crumpled loosely like a tuft of dacron would be.
4) The quick 1 in 14" twist encourages the use of long bullets.
5) I couldn't get far enough away from a scope - I tried one, cricked my neck back as far as I could, and let fly - it still hit me in the forehead. Not enough to cut, but enough to let me know it was a bad idea.
So - where I'm going with this story is - A mould came up on ebay, NEI 458-510-GC, which casts a long straight-sided bullet with a stubby (2R maybe) ogive, and a gas check. I thought it would be a great bullet for the .458 Mag., so I bought it and cast some bullets and loaded them with 52.0 gr. Scot 4065, purportedly a 4064 analog. The bullet is 1.6 inches long.
This gun has always been a tackdriver with cast bullets, and this load is no exception. I took it along today whilst experimenting with a muzzleloader, and shot a 3-shot group at 100 yards with the new bullet just as the light was fading about quarter to four PM (here in coastal Maine). Bear in mind this is with open sights. Two shots were touching in the 10 ring of an SR target, a third shot was a nine 1.8 inches away. That was about as much fun as I could stand from the bench, and the light was getting very poor, so I wrapped up the session & came home with a good feeling and a bragging target.