I have just purchased a new/used Remington 798 in 458 Win Mag, and have a supply of A2230 powder on hand, with some 405 gr cast FN lead bullets. Can I use a 60-70% fill with this powder to achieve 1600-1900 fps with the 405 lead bullets safely? The start load in the literature is only a 90% fill load.

this is 45/70 data
38.5 grs should give about 1550 fps in a 24" bbl.
43.0 will be about 1700.
with a 405 gr lead boolit.
max pressure will be bout 27,500 p.s.i.

a g/c is recommended in this velocity range for best results.

i have used some reduced loads of 2230 in other cartridges with good results.
the only thing i have found is when using mag primers when it gets hot the pressure starts to climb also.

Thanks, Lamar.