I will be loading 450g Swift A- Frames and 450 Woodleigh Hydros in my 458 Lott. According to the manuals, both of these powders work with both bullets. Any experience with these?

I tried H335 in my Lott but settled on IMR4320.
Better grouping and it seemed to me the 335 sent a fire ball out the end of the barrel.
Never tried Benchmark.

458 LOTT 510 WIN--bullet charge---82.5/W748 velocity-----2125

h335 -- always

Take a look at Michael's data:

http://m.b-mriflesandcartridge...0Data%2012232013.pdf

H335 is pretty temperature sensitive if that is an issue for you; not sure about Benchmark, but I tested H335 some years ago and got much higher velocities in with hot bullets vs ones very cold.