Loads for .458 Winchester Magnum

Doug Hamilton

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OK, I know that I'm going to catch a lot of grief for this, so please don't bother to tell me that I need a Lott. I used my .458 Win. Mag. to take exactly one cape buffalo bull on my first safari and I love the rifle. I'm going back to find another bull next year and the Winnie is going with me.
Now then, when I went before, I was using some older factory ammunition which I now know was not a good idea (although the bull died and the bullets didn't bounce along the ground to reach him).
I now reload for all of my hunting rifles and this hunt will also be "home-rolled." I am looking for good loads that aren't overly compressed or temperature sensitive yet still deliver the velocity that it was supposed to (2150 fps with 500 gr. bullets). The main problem with inconsistent velocities in this cartridge seems be around the use of tightly packed spherical powders which clump and don't burn evenly. I know some of you with more big-bore experience than I have an answer to this issue. Help please!
 

Ray B

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I have found the solution to "the problem" with the 458 Win Mag is to seat the bullets out to a slightly longer overall length. I have a Win M70 and the only thing needed to accomplish this was to remove the spacer from the magazine. the other solution that I find as effective is to use 480 grain bullets. If you aren't able to extend the OAL and must use 500 grain bullets I'd suggest Re7. I have heard that it is more temperature sensitive than the single base extrudeds and I haven't been in any extended hot weather to test them, but I have had no problems with it. If single base is needed some of the powders from 3031 to 4320 may provide the ballistics. If the 458 Win Mag didn't have enough horsepower for me then right on past the Lott and get something such as a 450 Dakota but for me, the Win Mag is fine.
 

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Hi Doug,

The .458 is my absolute favourite caliber and I have a hand-load that has worked well for me.

My hand-load is as follows;

Winchester Case
Woodleigh 480gn RNSP
74gn of AR2206H (H4895)
CCI Mag primer
@2150fps (chronographed by me in a Zastava M70 with 24" barrel)

This is just a fantastic load. NEVER had a pressure problem, cloverleafs 3 shots at 50m and little compression.
The bullet just sits nice and snug on the powder... just perfect.

But there is another load that should prove at least as good and that is;

Winchester case
480 gn Woodleigh RNSP
74gn AR2208 (Varget)
CCI Mag primer
@ estimated velocity 2150fps

With 450-500gn projectiles these 2 powders it seems can be substituted for one another.
Same powder and same powder charge for the same velocity - but AR2208 (Varget) does it at slightly lower pressure.

If anyone gives you grief about using the .458 tell them to mind their own business!
The .458 has killed countless thousands of elephant and buffalo and I have personally corresponded with PH's that have used it without problem on DG.

Good luck and keep us posted (y)

Russ
 

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Timbo

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Hi Doug,

I use a similar load to Russ. My pet load being Woodleigh 500gr RNSP or FMJs, driven by 72gr of AR2206H powder. I also roll crimp at the cannelure. Both these projies have the same SD with a very slight difference in BC. At 50yds this load gives me superb accuracy: cloverleaf groups with each projie, and each group almost touching.

I've taken various DG in Zambia, Zimbabwe and South Africa under varying climatic conditions - and even big game (water buff) in NT - without any problems. As long as you reload intelligently, the 458 Win Mag is enough gun for any occasion.

FYI, while in Zambia I met another PH in camp who was very enthusiastic about Woodleigh's 480gr RNSP and FMJs, when he heard I was using a 458 Win Mag. From his direct experience he was unequivocal: it's simply the best projectile weight for the calibre.

Cheers!
Tim (y)
 

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OK, I know that I'm going to catch a lot of grief for this, so please don't bother to tell me that I need a Lott. I used my .458 Win. Mag. to take exactly one cape buffalo bull on my first safari and I love the rifle. I'm going back to find another bull next year and the Winnie is going with me.
Now then, when I went before, I was using some older factory ammunition which I now know was not a good idea (although the bull died and the bullets didn't bounce along the ground to reach him).
I now reload for all of my hunting rifles and this hunt will also be "home-rolled." I am looking for good loads that aren't overly compressed or temperature sensitive yet still deliver the velocity that it was supposed to (2150 fps with 500 gr. bullets). The main problem with inconsistent velocities in this cartridge seems be around the use of tightly packed spherical powders which clump and don't burn evenly. I know some of you with more big-bore experience than I have an answer to this issue. Help please!
I have had great consistent groups and no problems with H335. Look up load data from Hornady This is Not a compressed load and you get a 500 gr at the desired 2150 fps
 

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I recently had my self-loaded .458 officially measured.
Also with the .480 gn bullet weight.
But all European components, that probably don't mean anything to you.
I' am also at 2.150 fps and still 14.500 psi below maximum.
Think .480gn is the best choice for .458
Any idea why it was created with 500 gn ?
 

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I recently had my self-loaded .458 officially measured.
Also with the .480 gn bullet weight.
But all European components, that probably don't mean anything to you.
I' am also at 2.150 fps and still 14.500 psi below maximum.
Think .480gn is the best choice for .458
Any idea why it was created with 500 gn ?
Good question! I don't really know. My guess is that possibly back when it was being developed, a 500gr bullet was regarded as the standard weight from a 458-cal to throw at DG - given the available powders at the time.
 

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I don't think it was though, as the .450 Nitro Express used 480 grains. Was there another popular .458 before Winchester introduced their magnum? My guess is they wanted to "beat" the NE by going to a heavier bullet but driving it to the same velocity.
 

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It's been a while since I messed with the 458 WM. But a couple of things to consider. The 458 WM requires enough neck tension or good crimp to hold bullet against recoil set back from being hammered against front of magazine. You can seat bullet out quite a bit for more case capacity but that will decrease neck tension and may not put crimp groove in proper place for crimping. The chances of set back are enough to cause concern for any serious DG ammo loading. If for just paper or plinking, then no concerns about set back so they can be loaded one at a time for no worries... except max chronograph readings to be posted online :)

I'd try 450 or 480 gr bonded bullets. Monolithics, except in much lighter weights, may be problematic because of length but I know banded monos generate a lot of neck tension- a good thing for no crimp groove seating and shallow seating. I'd try Varget, H4895 and Benchmark. Use a chronograph, published data and work up toward REALISTIC velocity objectives while watching pressure signs and reliable cycling. Good luck
 

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I am currently using AA2230 as my go to powder in the 458WM with 450-500 gr bullets with the 500gr at 2145 in a 24in barrel. with a load density of 98% so I am not compressing the powder.
 

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Doug Hamilton

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Hi Doug,

I use a similar load to Russ. My pet load being Woodleigh 500gr RNSP or FMJs, driven by 72gr of AR2206H powder. I also roll crimp at the cannelure. Both these projies have the same SD with a very slight difference in BC. At 50yds this load gives me superb accuracy: cloverleaf groups with each projie, and each group almost touching.

I've taken various DG in Zambia, Zimbabwe and South Africa under varying climatic conditions - and even big game (water buff) in NT - without any problems. As long as you reload intelligently, the 458 Win Mag is enough gun for any occasion.

FYI, while in Zambia I met another PH in camp who was very enthusiastic about Woodleigh's 480gr RNSP and FMJs, when he heard I was using a 458 Win Mag. From his direct experience he was unequivocal: it's simply the best projectile weight for the calibre.

Cheers!
Tim (y)
Thanks!
 

Doug Hamilton

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I have had great consistent groups and no problems with H335. Look up load data from Hornady This is Not a compressed load and you get a 500 gr at the desired 2150 fps
Thank you!
 

Doug Hamilton

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I recently had my self-loaded .458 officially measured.
Also with the .480 gn bullet weight.
But all European components, that probably don't mean anything to you.
I' am also at 2.150 fps and still 14.500 psi below maximum.
Think .480gn is the best choice for .458
Any idea why it was created with 500 gn ?
I am not really sure, but as I understand it, Winchester wanted a load that would duplicate the power of the .470 NE in a standard length bolt gun. A 500 grain bullet at 2250 fps.
Cheers,
Doug
 

Doug Hamilton

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It's been a while since I messed with the 458 WM. But a couple of things to consider. The 458 WM requires enough neck tension or good crimp to hold bullet against recoil set back from being hammered against front of magazine. You can seat bullet out quite a bit for more case capacity but that will decrease neck tension and may not put crimp groove in proper place for crimping. The chances of set back are enough to cause concern for any serious DG ammo loading. If for just paper or plinking, then no concerns about set back so they can be loaded one at a time for no worries... except max chronograph readings to be posted online :)

I'd try 450 or 480 gr bonded bullets. Monolithics, except in much lighter weights, may be problematic because of length but I know banded monos generate a lot of neck tension- a good thing for no crimp groove seating and shallow seating. I'd try Varget, H4895 and Benchmark. Use a chronograph, published data and work up toward REALISTIC velocity objectives while watching pressure signs and reliable cycling. Good luck
Thanks.
 

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I have reloads with 450 gr and 480 gr Peregrine copper monolithics. Have used Somchem S 321 with those bullets (South african powder) according to the peregrine reloading recommendations (around 72-73 grains-dont have the details to hand). I chronographed the two loads at 2223 fps with 450 gr and 2140 fps on a cold day at the range over the weekend (Labradar chrono @ approx 16-18 degrees c/25 " barrel bored to Lott)

You can also get similar velocity with conventional solids-Woodleigh do a 480 gr bullet with crimping canelure set back on the bullet as well as 500 gr. Hornady DGS solid will work. So you can choose between a modern flat nose copper monolithic around 450 to 480 gr or old school lead and jacket 480-500 gr- all of which can get to 2150 and more. I also use Vihtavuori check out- https://www.vihtavuori.com/reloading-data/rifle-reloading/?cartridge=58. I am using their powders in my win mag now bored out to Lott. also keep in mind that a good powder at around 100 -103 % or lightly compressed is often consistent and reliable. I think the type of powder is more important than the compression.
 

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Doug Hamilton

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I have reloads with 450 gr and 480 gr Peregrine copper monolithics. Have used Somchem S 321 with those bullets (South african powder) according to the peregrine reloading recommendations (around 72-73 grains-dont have the details to hand). I chronographed the two loads at 2223 fps with 450 gr and 2140 fps on a cold day at the range over the weekend (Labradar chrono @ approx 16-18 degrees c/25 " barrel bored to Lott)

You can also get similar velocity with conventional solids-Woodleigh do a 480 gr bullet with crimping canelure set back on the bullet as well as 500 gr. Hornady DGS solid will work. So you can choose between a modern flat nose copper monolithic around 450 to 480 gr or old school lead and jacket 480-500 gr- all of which can get to 2150 and more. I also use Vihtavuori check out- https://www.vihtavuori.com/reloading-data/rifle-reloading/?cartridge=58. I am using their powders in my win mag now bored out to Lott. also keep in mind that a good powder at around 100 -103 % or lightly compressed is often consistent and reliable. I think the type of powder is more important than the compression.
Thank you for sharing the information!
 

Nhoro

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Thank you for sharing the information!
And although I now have bored out to Lott it was mainly because I hoped it would help with feeding (it did slightly but I still had to work on the action) and because the rifle was already at the gunsmith and he offered to do it pretty much for free. Now I dont have any Lott brass so I am happily shooting win mag ammo. The 450 gr loads were given to me by a friend-they do elephant population control on the property and used the 450 gr happily on big bulls. Not sure how many but my brother has taken 12 -same company- with his 416 Rigby. So anyone who tells you they don't work, I have it from an experienced horses mouth that they do ! You can check out the Peregrine website-google peregrine bullets- and they will give you loads with South African powders.
 
 

 

 

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