Load Data Request: 458 Win Mag

[creophus]

I want to load some 458 Winchester Magnum with 385gr cast bullets. I have Varget, Benchmark and Win 748 on hand. I'd like to use one of those.



Any help would be greatly appreciated.

[runfiverun]

if nothing else you can start with some 45-70 data and go from there.

[creophus]

True, but I'm worried about the difference in case length would either cause ignition or pressure problems.

[runfiverun]

if using the faster powders they are generally position insensitive.
2400 may or may not need a filler, i use one in my 45-70 [the only time i use one with 2400]
if using like h-322 through 4064 or so, a filler will be wanted to keep ingition consistent.
benchmark would want a filler as would the varget, the 748 may shoot better with one.
remember to lower the powder weight by the weight of the filler used.
and that the filler touches both the powder and the base of the boolit with some compression from seating.

[creophus]

Thanks for your responses, I don't use fillers so far and would rather not stop. If it comes down to it, I'll just get some different powder. :(

[runfiverun]

don't give up on them without trying.
in my 8 mauser for instance i get some vertical stringing at 28.5 grs I-4895, adding a filler fixes that.
but so does going to 30 grs of the same powder,without a velocity change that's noticeable.
fillers aren't evil gun wrecking things, they are a tool to be used to improve some situations,and to fix other issues.
i prefer a filler for hunting loads,and my most accurate target loads use them.
i can usually find another load that's close enough without one.