Well, my custom Mauser in 458 Win Mag is done and sighted in with my chosen hunting load...A-Square's Triad load which uses a 465 grain bullet. I'm now looking for data on a good practice load that comes close to the same point of impact at 50 yards. Does anyone have experience with such a load?
Keith
cprher@verizon.net

Here's some very limited info.

In my rifle, which is likely different than yours, the 405g rems at about 2000fps with imr 3031 shoot at about the same point as 500g win factory loads. If I recall correctly, the one box of A square solids that I shot were also at the same point of impact, but I never compared the 400g and the A square on the same day.

Anyway I would start with 405g rems, just because thay are so cheap. If you want heavier recoil with your practice loads, you can load these well above 2300 fps. I've done this (I believe with H4895), but in this case the POI did change compared to 500g factory loads.

Probably not much help, I think you'll just have to try with your rifle. Its the fun part.

I have the 458 Lott. I loaded some 458 Win Mag 500gr bullets and they went 2153fps. Where as those 500gr bullets go 2280 out of my Lott.

I have never shot the A Square Triad, but here is what I can offer. 56.5gr of IMR4227 and a 350gr Hornady RN hit same POI as my 450gr A Frame Rel 7 load with a substantial reduction in recoil.