Need cast bullet advice for .458 Win Mag

[Bishopus]

I've been casting up pistol bullets--240 and 300 grain for .44 mag, and 230 grain for .45 ACP--for a whole month now, and so far I'm very impressed. Cast bullets are accurate, cheap, and very fun to make--I'm starting to enjoy casting as much as loading. I think I'm ready to move on to casting for some of my rifles, starting with a Win 70 Safari Classic in .458 Win Mag.

Can anyone with experience casting for the .458 point me in the right direction for a good bullet design, and talk me through the details? I'm hoping to cast up something in the 500 grain range at around 1700-1900 fps, but most of the molds are 350-405 grains and set up to feed through a .45-70, at more moderate velocities.

Should I use pure lino? A softer or harder alloy? Gas checks? Heat treatment? Will Lee tumble lube work at these velocities and pressure levels? Thanks for your help!

 

[44Bore]

With a 458 you can duplicate all load levels--from a 45 colt to full power 500 grain loads. I would stick to gas check designs in the 350-400-500 grain ranges. You should not need pure lino bullets to keep leading down. Make sure bullet is sized to the groove diameter of your barrel and make the alloy/heat treating match your intended use and desired velocity range. I shot quite a few RCBS 350 and 405 grain flat nose bullets at around 2000 fps when I had my 458. I used to keep some full power 500 grain loads around to sort the men from the boys at the range though.

fwiw, 44Bore

 

[Johnn Peterson]

There's a variety of cast bullets I'm using in a Marlin .45-70 and in a Marlin 444, in addition to the cast I use in handguns.
I've started trying a few cast loads in a model 70 in .458WM. The first didn't work out too well. The bullet I was using was very similar to the Lyman #457125, a RNPB weighing 525grs. I'd have to classify my initial results with that particular bullet as dismal. There are a number of accuracy designations, the most popular or well known is M.O.A., Minute Of an Angle. A shooting buddy from Ladysmith has a category, one step below that, M.O.H.P., Minute Of a Hockey Puck. There's one level below that, which describes the accuracy I got with that bullet. M.O.T.S., Minute Of a Toilet Seat. Needless to say, they weren't working out at all.
A bullet that has worked well in the .45-70 is a .420gr FNGC that looks much like the RCBS #82054. I next plan is to try this and another I've just obtained of the same configuration but weighing 530grs.
I don't cast for myself any longer but get all my cast rifle & pistol bullets from a couple of local suppliers. I was never too fond of casting at the best of times.
For bullets of that size/daimeter I like them hard cast and if possible, sized 0.001"-0.002" greater than the bore diameter.
The problem with the first bullet I mentioned, even though they were light loads, may have been a combination of a number of things. Hardness, sized to the same diameter as the bore but probably more than anything is the actual amount of lead contacting the rifle lands. With that particular bullet there isn't much.
Another avenue to consider, that another shooting buddy from Ladysmith has tried and works well especially on light loads, Patching Cast Bullets with Teflon. I have an article he gave me from the Handloader 86 by Curtis L. Wilson. The process is a little time consuming but apparently the results are worth it. The basics are wrapping an unsized cast bullet with a few rounds of teflon tape.
Also, check out the Beartooth Bullets website as I've found they have a lot of good cast bullet related info.

 

[ben hunchak]

The Lyman #457193 and 457102 are standards for the .45s, we use Lymans, Saeco, Hoch, Nei, Paul Jones, RCBS, etc. The Lyman are 1 cav. only, NEI have alot of heavyweights and multi-cavity molds and i would check them out on the net. I find that with the large calibers Gas checks are not as crucial for higher vel. but others might disagree. I will mention one other that we use, the LBT designs, the meplat is so wide that it can cause feeding probs. in the Marlin. You may also be interested in "the .458 Win Mag. Journal" authored by Cdn. B. Mitchell, he explores upper end loads for the .458 with jacketed and cast bullets.