.458 Winchester Magnum J-word question

[Just Duke]

I had 400 Barnes TSX 500 grainers showed up as a gift from wifey for my .458 Win Mag.

Here's what the J-word data says
Bullet Weight: 500 gr Case Trim Length: 2.490" S.D. 0.341
Bullet Style: Barnes Banded Solid
H4198 49.0 Grains 1857 55.5 Grains 1999 93 http://www.barnesbullets.com/images/458WinchesterMagnumWeb.pdf

Here's what the Hodgden data reads and the load I want to try.
510 Grain Winchester Spire Point
IMR 4198 44.5 grains 1645 52,400 CUP

Am I in the safety zone substituting bullet styles? I have in my inventory 4 IMR 4198's and 6 H4198's 8 pnders that I would like to use.

[btroj]

I would send an email to Barnes and ask for some load help. I have found them to be good people to,deal with. Much safer than playing with substituting bullets with very different properties. The Barnes TSX, being solid copper, can be a bit funny about pressures.

[44MAG#1]

That data was developed by DuPont years ago for the 510 gr bullet. Hodgdons just copied it to their website.
That load is low, very low I don't care what the CUP's are. I know from experience with the 458 Win Mag and jacketed bullets it is.
If you will look at data that lists BOTH IMR4198 and H 4198 you will see both are very close.
Sometimes they flip flop with one being SLIGHTLY heavier then the other.
While being safe is paramount reloading isn't a science that only a ballistic tech can understand.
This is what I would do. I would take Barnes data for the H4198 and start at STARTING load and work up to the full load if I wanted to go that high. I would get a standard for pressure using the H4198 powder then I would start maybe 3 grains lower with the IMR4198 than Barnes START load using H4198 and creep up a 1/2 grain at a time until I matched the H4198 load and call that my IMR 4198 data for that bullet.
If you are careful and can compare pressure signs and especially if you have a chronograph and if you use your noggin you won't have any problems.
This is just me though.
Do what you want. It depends on the confidence you have in yourself and your baseline of experience in reloading.

[Grandpas50AE]

I loaded the Hornady 500 gr. RN for my M77 Ruger back in the 80's for a moose and black bear hunt in Alaska. I had good groups with it using a CCI 250 primer and 69.0 gr. of IMR 3031 producing a factory duplication load of 2148 fps.