Interesting, I had a .458 with a 15" twist - was supposed to be 14" but was 1" slower than that, as well as 18", 20" and 22" twists - never a 24" in .458, though.

Every twist I've used in the .45's shot all bullet weights up to 500gr. beautifully, with the faster 18" and 20" handling bullets at low BP velocities of 1,500fps (3 1/4" & 2.750" and less with 2.4" and down to 1.9" cases.

I did shoot the Lyman #462560 form my .458- at over 2,000fps, and it was quite accurate at that speed, in the fast barrel, but also in the slower twist barrels. That 15" twist barrel, however did not like any 300gr. bullets if driven at or over 2,400fps. - at all as they would cut oblong holes in the target. I always felt it was due to the rate of twist being too high for that bullet's length - right or wrong, it wouldn't shoot them at that speed, but did well with them if driven no faster than 2,200fps. Perhaps the jacketed bullet's composition was causing too much slumping and that was the cause - at that pressure level.

Another puzzler is the 15" twists in .50 calibres. Why? I just don't get it. A 24" twist will stabilize and shoot with match accuracy, up to 600gr. bullets - even at low speeds, let alone 800fps faster at smokeless speeds.