Handloading 458 Win Mag

Nathan

New member
This caliber seems to have a bad rep for compressed loads in all powders and bullet weights, marginal >2.5” accuracy, and even trouble with misfires, although, I think the misfires are old information at this point.

If you load for this:
What is your load?
How is it to put together your loads?
Do you crimp? If so, with what die?

Any advice? I’m mostly planning on full power loads, if I go this way.
 
If you are gonna run full horsepower, a lot of your loads will be compressed.

I use H4895 in all my big bores with jacketed bullets mainly because I have a lot of it. It works for me.

Accuracy is what you can get out of it, but mine will do 1 1/2" @ 50 yds. with open sights.

I have shot at 100 yds but it is hard to hold in a standing position and I will not shoot it from a bench. I DO use a shooting stick when standing, which is nearly all the time.

A buddy bought one years ago and his first trip to the range using factory ammo damn near ripped his thumb off as he was not ready for what ensued. He had to have reconstructive surgery on his hand.

Both of us shoot mostly cast bullets nowadays in all the big bores just because cast is just as effective, just as accurate and you can throttle it down easily.

His son bought a Weatherby 460 and shot the barrel out at 2200 rounds just because he didn't believe in shooting less than full horsepower loads.

You asked about crimping: I always crimp the big bores. I use the standard RCBS dies as with all other cartridges that I load for.

I really "enjoy" shooting the 460 much more than the 458.

If you are planning to purchase one, I strongly urge you to be fitted for a stock. These big bores guns will hurt you if you don't have a good stock.
 
I used Winchester 748 ball powder for years and never had a problem in Africa or anywhere else. The one problem I did have while hunting in Cameroun was that my .458 WM Ruger had a magazine box that was a bit too short for the 500 gr. Hornady solids I had with me, so I couldn't crimp them in the cannelure. Under the circumstances I had no choice but to use an extremely tight case neck and seat the bullet as compressed as humanly possible on top of the powder. That set the bullet back just that 1/16" I needed so that they would not hang up in the magazine. Certainly not recommended loading procedure but it worked just fine and I never had a problem. I tested it sufficiently to ensure that the bullet would not ever creep forward in the case during recoil. Anyway, back in the bush in those days I didn't have any other options. All this just to say 748 ball powder is still a favorite of mine.
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Ecc 11:4 He that observeth the wind shall not sow; and he that regardeth the clouds shall not reap.
 
This caliber seems to have a bad rep for compressed loads in all powders and bullet weights, marginal >2.5” accuracy, and even trouble with misfires,

Other than compressed loads, which sometimes ARE the right thing to do, I've never heard any of that about the .458 Win Mag. Where did you hear all those things???

The only things I've ever heard bad about the .458 Win is that early ammo had a lot of failures of the bullet jackets, (a problem that went away after Joyce Hornady came back from a safari,) the common problem of the factory claiming higher velocities than the round delivered, and some complaints about ball powder, and its sensitivities. Also heard complaints about the ball powder used and its poor performance in Africa.

As far as I know, bullet and powder issues were essentially fixed decades ago.

Never heard of any accuracy issues due to the design of the cartridge. Generally speaking, big bore rifles are surprisingly accurate, BUT few people can shoot them that well, with full power loads. Plus, a .458 is not intended to be a long range round, so maybe some rifles weren't built with maximum possible accuracy in mind.

My .458 will overlap 3 shots at 100yds, with some loads. Also consider that a 5 shot group of .45 caliber holes can be 2-2.5" across and still be one ragged hole.

Most .458s have some variation of "express" sights, and aren't fitted with target grade triggers, so shooting sub-moa groups isn't as simple a matter as it can be with guns built differently.

As an example, I can get sub-moa from my 14" scoped .30-30 T/C Contender, but even that same ammo won't shoot sub-moa from my Winchester 94. The cartridge might be capable but if the gun isn't then it isn't.


Most of what I shoot is 400gr cast slugs at 18-1900fps. Works for anything I might meet in North America, and while I can load elephant loads, I don't bother. Sorry, I don't have the exact load data handy.

I did load a box of Speer 400gr flatpoints at 2100fps. That Speer bullet is made for the .45-70, and is overdriven at 1800fps+ and seriously overdriven at 2100. Doesn't seem to expand as much as explode at that speed.

The Hornady 350gr RN on the other hand IS built to give good controlled expansion at that speed (and 2100fps is far short of the 25-2600fps that the .458 could do with that bullet, loaded to max.

Bullet selection is important for what you want it to do. Shooting a deer with the 510gr softpoint "Lion load" is kind of wasteful. Using the .458 Win case to launch a cast slug at hot .45-70 speeds works great, and is less wasteful especially in $.

My loads are assembled the exact same way I do all my other ammo of the same type (straight wall rifle round). I don't bother with any of the "tricks" used to make match ammo as accurate as possible, there's no point to it, for me and what I do with the gun.

I do crimp. Heavily. Using the standard seater die. When firing heavy loads in bolt actions, rounds in the magazine can be slammed back and forth, and a good crimp helps prevent bullet "setback" in the magazine.

My .458 is a custom built (aka sporterized) Mauser, I found at a gun show. No idea what the guy who had it built had in mind, but its not set up to be a dangerous game rifle.

I don't load or shoot "elephant loads", nor do I buy factory ammo (waay too expensive for me) but if you can afford it, and want to, then by all means, enjoy! (I do have a couple boxes of 500FMJ that I'll probably never load, just in case, you understand...)


The .458's straight case doesn't do well with the slowest powders. Medium burn rate rifle powder (or even the faster ones) are the way to go in that cartridge.


Hope this helps
 
There's nothing wrong with a compressed load. In many ways, compressed loads can be argued to be superior to those with an air space. Most notably, ignition is extremely consistent.

Accuracy is a matter of rifle (mostly barrel) quality and condition. The cartridge is not to blame.
But, of course, with the big boomers, most people tend to flinch badly enough that even the best rifles don't appear to perform well.

Misfires?... Again, not the cartridge's fault. Bad ammo. Bad reloading practices. Or a problem with the rifle.


I've shot quite an assortment of 'big boomers', on up to .458 WM, .416 Rigby, .450 Nitro, and more.
All of them were capable of more accuracy than myself. (The human is usually the weak link.)
The .458 WMs and .416 Rigby, in particular, were known for stacking those big bullets right on top of each other - to the point that the shooter sometimes wondered if they missed the target entirely with subsequent shots.
 
If memory serves me... it wasn't just a compressed load issue... It was much more of a the powder clumped together issue.

Wiki... ( I know ) states it better then I .

"By 1970 issues with the cartridge began to surface. Winchester had been using compressed loads of ball powder as a propellant for .458 Winchester Magnum. Due to clumping of the powder charge and the erratic burn characteristics associated with such loads, performance of the cartridge came into question. While Winchester addressed this issue, the stigma remained, and the cartridge’s performance on dangerous game was suspect. However, the .458 Winchester Magnum remained the standard of measure for dangerous game cartridges. "

And that could lead ( and may have ) a round that doesn't ignite or burn correctly.

Not something I would like in a Dangerous Game Cartridge.

That said... it may have been a variety of reasons.. not quite enough primer... etc.
 
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This caliber seems to have a bad rep for compressed loads in all powders and bullet weights, marginal >2.5” accuracy, and even trouble with misfires, although, I think the misfires are old information at this point.

If you load for this:
What is your load?
How is it to put together your loads?
Do you crimp? If so, with what die?

Any advice? I’m mostly planning on full power loads, if I go this way.
I sold mine. It is an Elephant rifle, so 2.5" at 100 yds is perfectly acceptable; actually quite good, considering the average shooter is probably 1" of that 2.5". Mine kicked like a mule with steel shoes. My 460 Wby was more pleasant. I never had a misfire in it. I used my Rcbs seating die to crimp. I honestly don't remember if it was a roll or a taper. I think I shot W748 with 500 round noses.
 
I'm currently doing 3 full power reloads for my 458WM using H4895:
405 Rem - chronos at 2,275 fps
450 Barnes FN solid - chronos at 2,175 fps
450 Swift"A" - chronos at 2,160 fps
all are compressed (at about 102 to 103%)
Use "Heavy" Crimp with a Lee crimp die.
note: Lost 70 fps on each load when barrel was shortened from 26" to 23". The 405 is just for less expensive practice.

If I were just starting over, I'd try both H4895 and AA2230.

Nathan, your welcome to PM me for any questions.
 
Anyone that shoots the 458 full power has my admiration.

I shot my 7mm Rem Mag before I sold it to be sure it was working.

I had not hunted or shot it in 10 years. Arghhhhhhhh. Mother of (deity of your choice)

I was younger and tougher when I was, sigh.
 
Accurate 2230 and Ramshot Exterminator are the "go to" powders for the 458. They are ball powders with great loading density so you get top velocities without having to crush the powder down into the case. By using mono-metal bullets you can get extra velocity without giving up penetration by loading the 420-450 grain bullets instead of the 500s. The 458 Win Mag has never been better than it is right now.
 
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