Another 458 Win Mag thread

Foxi said:

is already amazing

.450 NE

.465 NE

.470 NE

all in the same weight and speed class.

Everything is fine and much praised.

When the same energies come out of a .458 WM barrel, it just sucks

Click to expand...

It's funny how that works, isn't it?

CBH Australia said:

That statement is incorrect!
The Woodleigh factory burned down and they are in the process of rebuilding and plan to reopen.
I have followed this closely and gone to the source on more than one occasion.

FYI, I also hunted with @Badboymelvin ladt week.

Click to expand...

Yep! It was a great hunt bro!

Russ

Well we know @Badboymelvin took a .458. What did you hunt? What rifle did @CBH Australia take?

Forrest Halley said:

Well we know @Badboymelvin took a .458. What did you hunt? What rifle did @CBH Australia take?

Click to expand...

Wrong, my friend!

We were hunting Fallow and long shots were a real possibility so, I took my beautiful (in my eyes anyway!) Winchester M70 Synthetic Matte .338WM
(shooting the 180gn Woodleigh PP @3100fps)
and
My Lee Enfield sporting rifle in .303 British
(shooting the 180gn Sierra SP at a very lazy 2160fps. This was the load that came with the rifle and once I have enough empties I'm going to stoke these hopefully up to 2400-2500fps)

That .338 load is like a freaking laser beam and it drops deer on the spot - so that was the first rifle I grab on hunts like these.
In regard to the Lee Enfield sporter, it is on my bucket list to bag a deer with the wonderful old .303, so that's why the old girl came along

I have taken the .458 to this spot in the past, but thought I'd give my shoulder a rest this trip!

@CBH Australia took his stunning custom 280AI and I'm pretty sure he was shooting the Woodleigh 140gn PP.
It sure did the job on his Fallow and his rifle is well worth a write up on here, if he hasn't already... WOW!

Russ

Foxi said:

is already amazing

.450 NE

.465 NE

.470 NE

all in the same weight and speed class.

Everything is fine and much praised.

When the same energies come out of a .458 WM barrel, it just sucks

Click to expand...

That always makes me chuckle “well it’s no good because it’s from a .458 win mag” but it matches the same ballistics as the above mentioned cartridges…. Reminds me of the people that fall back on “doesn’t matter with this baby! If you hit them in the tail it’s so powerful it’ll nock’em flat”!! While they manage to gut shoot every animal they point it at and flinch before the triggers even pulled…. Yep….. it’s the cartridges fault…….

Foxi said:

is already amazing

.450 NE

.465 NE

.470 NE

all in the same weight and speed class.

Everything is fine and much praised.

When the same energies come out of a .458 WM barrel, it just sucks

Click to expand...

I posed that question to someone who was poo pooing the 458 wm, focusing particularly on the 450ne, and the response was crickets.

Also take the lott for example. Compressing powder in the WM is bad, but doing it in the Lott is okay.

Badboymelvin said:

All this talk of the .458 has inspired me to get my backside into gear and load up some ammo!
Here's some 450gn Hydro's loaded in front of some BM2 (BENCHMARK) powder that I loaded up today.


View attachment 463559

Click to expand...

I once read an account of an elephant being taken with a hydro. Apparently it was so devastating their was biological, read brain matter coming out of both ears from the frontal brain shot. I can't see or hear of a hydro without thinking about that.

Pieter Visagie said:

Hi Guys

I'm interested. There are plenty of people with very strong opinions about the 458 Win Mag on this site. Why is it that people question the ability of the 458 Win Mag, but not the ability of the 470 NE. Both calibres shoot essentially the same projectile (well, give and take a few thousands of an inch) - 500 grain @2150fps. Why is it that some seems to hate the Win Mag, but nobody seem to judge the NE? Or am I missing something?

BTW. If all goes well I will buy a Pre64 458 Win Mag Super Grade tomorrow. Why? I want to see a bit more reaction when I shoot a Ele in the head. I've had my chance on a few desert bulls in Bots and next I want to try my hand on a tuskless cow in Zim. Hunting Ele's are a special type of addiction. I can't think of anything that both terrifies and excites me as such at the same time.

Click to expand...

@Pieter Visagie
The person with all the knowledge on the 458 WM is @Badboymelvin.
What he doesn't know about the 458 and how to get the best out of it could be written on the head of a pin. Plus he is a nice bloke

JanP said:

@ Sarg. If you have nothing to say about the calibre on Ele just refrain from answering.
Although You were quite right about 458Win bashing by people that never shot this calibre in real life.

Click to expand...

@JanP
That's not very nice to @Sarge.
He gave an honest and valid statement on it use as HE sees it.
He may not have used it on ele but at least he has used it and effectively by the sounds of it.
Please play nicely on our forum.
Bob

Bob Nelson 35Whelen said:

@Pieter Visagie
The person with all the knowledge on the 458 WM is @Badboymelvin.
What he doesn't know about the 458 and how to get the best out of it could be written on the head of a pin. Plus he is a nice bloke

Click to expand...

Thank you for the kind words Bob - but the person with the real knowledge on the .458 is Michael458.
He has helped me in the past and has always answered my questions and had time for me.

There a a slew of people on another forum who goes by the name of Riflecrank, CZ550, AussieGunWriter and others that are the real experts.

I’m just a hobbyist with passion!
I’m looking forward to our future hunt Bob.

Russ

Bob Nelson 35Whelen said:

@Pieter Visagie
The person with all the knowledge on the 458 WM is @Badboymelvin.
What he doesn't know about the 458 and how to get the best out of it could be written on the head of a pin. Plus he is a nice bloke

Click to expand...

Forrest Halley said:

Well we know @Badboymelvin took a .458. What did you hunt? What rifle did @CBH Australia take?

Click to expand...

Forrest,
I took my lightweight .280a.i. because I was hunting Fallow the previous week in another location. It was my first opportunity to hunt with it so it so I was keen to try it. Having travel and spending the weekend in the city limited my options for carrying multiple rifles.
I had been in touch with Russ regarding what we might do Fallow/Sambar a couple of weeks prior and decided the .280a.i. would be ok for Sambar depending the location we chose based on weather and time frame.
Russ took me to his secret Fallow spot, can't tell you where it is because it's easy to find and Victoria is pretty small.

Yes I used a Woodleigh 140gm ppsp because I found an accurate load and I ran with that. It was effective.

Badboymelvin said:

Thank you for the kind words Bob - but the person with the real knowledge on the .458 is Michael458.
He has helped me in the past and has always answered my questions and had time for me.

There a a slew of people on another forum who goes by the name of Riflecrank, CZ550, AussieGunWriter and others that are the real experts.

I’m just a hobbyist with passion!
I’m looking forward to our future hunt Bob.

Russ

Click to expand...

@Badboymelvin
Russ you may have learnt a lot off other and it is good to acknowledge that but because of that learning you are a font of knowledge.
Hopefully one day we will get together.
Bob

In a chronological order, here's the "why":

When Winchester released the .458 Winchester Magnum in 1956 , factory loaded ammunition had an advertised velocity of 2130 FPS (a chronograph test in an HP Laboratory in 1961 documents the actual velocity as being 2087 FPS, out of the 25 inch barrel of a pre '64 Winchester Model 70) . Loads were a 510 gr soft nose and 500 gr steel jacketed round nose FMJ . When Remington started manufacturing .458 Winchester Magnum factory loaded ammunition in 1961 , advertised velocity was also 2130 fps . Offerings were a 510 gr soft nose and a 500 gr steel jacketed round nose FMJ (with a thinner steel jacket than those offered by Winchester) .

Now , when fresh ammunition was used , These velocities were indeed accomplished (or at least, close enough to get the desired effect) . The problems arose with ammunition, which was a little old ( Like a year or two ) . The Compressed olin powders led to clumps . This resulted in erratic velocities ( Often lower than 1900 FPS ) . Bullets would also slowly get pushed out of cartridge cases , as well . This caused feeding problems in short actioned rifles ( FN Browning , Interarms Whitworth Express , etc ) .

In '73 , Winchester and Remington BOTH lowered the advertised velocity to 2120 FPS , in an attempt to increase shelf life . However , the problems were still there .

In '78 , Winchester and Remington Both lowered the advertised velocity to 2040 FPS , in another attempt to increase shelf life . Shelf life was improved , but now the Winchester and Remington factory ammunition was inadequate for frontal brain shots on big bull elephants ( and Matriarch cow elephants ) , and frontal heart shots on Cape Buffalo . Also was inadequate for Rhino and Hippo on land .

The Elephant cullers working for the game departments in the National Parks ( Like Clem Coetzee and Mike LaGrange ) in Zimbabwe ( Then , Rhodesia ) and the cullers working for Tseste Fly control and Cape Buffalo eradication culls found this out the hard way ( From the 1970s to the 1990s ) .

Art Alphin ( Owner of A Square ) decided to help the game departments , by providing them with specially loaded .458 Winchester Magnum ammunition . These were Remington Peters cartridge cases , loaded with 500 gr Hornady round nosed steel jacketed FMJ solids . They were loaded to early Winchester's original advertised velocities of 2130 FPS .

These were performing satisfactorily , but the original problems found in the pre '78 Winchester and Remington ammunition began to resurface ( Short shelf life ) .

In '87 A Square ditched the 500 gr Hornady round nosed steel jacketed FMJ solids , and began to load their ammunition with 465 gr monolithic solids . This accomplished a velocity of 2200 FPS . But again , if the ammunition sat around for a couple of years in a shelf or a closet , then velocities became erratic and the bullets started slowly getting pushed out of cases . A Square monolithics also caused excessive strain on rifle barrels ( Rifle barrels were getting shot out , only after less than 500 firings ) .

In 1992 , Federal started offering their Trophy Bonded Bear Claw and Trophy Bonded Sledge Hammer Solids in .458 Winchester Magnum . These used a 500 gr bonded soft nose or a 500 gr bonded steel jacketed round nosed FMJ solid . However , these loads accomplished little above 2000 FPS , and frequently below 1950 FPS . Also , when Jack Carter stopped being involved with Trophy Bonded Bullets , the bullet construction notoriously deteriorated .

After 1995 , Hornady started offered factory loaded ammunition for the .458 Winchester Magnum . This was called their " Heavy Magnum " line and were loaded with round nosed steel jacketed FMJ 500 he solids and 510 gr soft nose . Advertised velocity was 2230 FPS . How ever , shelf life was only 6 months . This high pressure ammo was also causing extraction problems on bolt action rifles in humid climates ( Like Zambezi Valley ) .

In 1996 , Remington stopped offering their 500 gr FMJ loading , altogether . The discontinued the offering , and only offered a 450 gr Swift A Frame loading , for a few more years . Then , they discontinued their .458 Winchester Magnum ammo line , altogether .

Finally around 2006 , Hornady fixed the problem by releasing their DGS and DGX line . These were a 500 gr Flat Nose bonded steel jacketed FMJ solid and a 500 gr soft nose bonded bullet . Advertised velocity is 2140 FPS . The shelf life problems have ( largely ) been taken care of . Because Hornady uses a special fine grain cool burning powder . However , you occasionally still get reports of fluctuations in velocity . Hornady DGS solids also have a small propensity to distort on Frontal brain shots or shoulder shots on big bull elephants and shoulder shots on Cape Buffalo .

The best solution nowadays is to hand load and ditch the 500 gr bullet , and use a 480 gr bullet ( As sold by Hornady and formerly Woodleigh ) .
These improve case capacity enough to solve the shelf life problems , permanently .

In 2009 , Winchester listed two different loads for their .458 Winchester Magnum factory loaded ammo :
- A 500 gr Nosler Partition Soft nose , which was advertised as only accomplishing 2010 FPS
- A 500 gr Nosler monolithic solid , which was only advertised as accomplishing 2010 FPS .

Needless to say , neither offering was a success. In 2010 , Winchester dropped their .458 Winchester Magnum ammo line , altogether .

Avoid monolithic solids in the .458 Winchester Magnum. Monolithic solids need to be longer than a conventional FMJ solid in the same weight ( In layman's terms : A 500Gr monolithic solid will need to be longer , than a 500Gr FMJ ) . Thus , increased powder space gets compromised . In a caliber like the .458 Winchester Magnum ( Which is already well known for case capacity issues ) , this becomes a huge problem . If you gotta use monolithic solids in the .458 Winchester Magnum, then stick to 450 - 465Gr monolithic solids . Nothing heavier .

I hope this helps.

Hunter-Habib,
Nice write up, but you forgot to mention the original H. P. White Laboratory tests in 1955.
Julian S. Hatcher, Major General U.S. Army, Retired was Technical Editor for the NRA's AMERICAN RIFLEMAN then. WRAC sent him "the pilot model" .458 Winchester Magnum and ballistics reports: "... no shortcomings in ballistics were noted." This was a recollection recorded in HATCHER'S NOTEBOOK.
His first article on the .458 WinMag in the NRA pub was entitled "For the Biggest Game" and subtitled
"A report on the .458 Winchester Magnum cartridge and rifle," in the August 1956 issue of AR.

The .458 WM exceeded all advertising claims regarding ballistics:
25" barrel
76 degrees F, 59% RH
Bullet: 500-gr WRA FMJ RN
COL: 3.340"
Winchester cases and Winchester 120 primers
Propellant: 71.0 grains of HiVel #2, NOT COMPRESSED
Velocity average for 10 shots: 2160 fps, intstrumental velocity 20 feet from muzzle
Pressure average for 10 shots: 50,410 PSI

Assuming G1 BC was 0.295, corrected to MV = 2174 fps
KE at MV = 5247 ft-lbs

Any of the terrible stuff that happened in the decades after that can be blamed on slobs of one sort or another, mostly at the ammo factories, but end-user abusers as well.

On March 9, 2022 test-fire and dissection of 1957 vintage ammo from WRAC was done by me.
Date code on end flap of the red and yellow Winchester SUPER SPEED box was 91MM8,
indicating Nov. 8, 1957 ammo lot date.
Advertised MV was 2125 fps for the WRAC 500-grain FMJ RN
This .458 WinMag factory load was 64 years and 4 months old when fired.

25" Shilen barrel
51 degrees F
Bullet: 500-gr WRA FMJ RN
COL: 3.331" (brass length = 2.494")
Winchester case, red sealant around primer
Propellant: 67.0 grains of extruded, small grain tubular, charcoal-grey-black color
5-yard chrono for 5 shots: 2072, 2072, 2061, 2065, 2059 Mean = 2066 fps
If G1 BC = 0.295:
MV = 2080 fps

Ammo was stored in homes with central HVAC climate control FOR OVER 64 YEARS.
If that had been HiVel #2 powder, 4 more grains of it might have been nice.
Anyway, not bad stuff, factory loaded before the Democrat voters took over the factory.

Nowadays powders and bullets are so advanced as to allow handloaders near endless options.

This is undeniable:
Load the .458 WinMag to same COL and higher pressure (MAP) as the .458 Lott
is allowed by SAAMI,
and the .458 WinMag will give higher velocity or lower pressure or both, compared to the SAAMI .458 Lott.
It is all in the throat and a bullet long enough to make the span.
Physics does not lie.
Slick up your action and you can work the longer action fast,
don't feel bad about using an H&H-length action for your .458 WinMag.

Here is a funny. The .458 Lott had its brass lengthened by 0.3"
and was meant for primary use in an action only 0.2" longer.
That is a bit cramped.
Don't get me started on using a 3.000" case length (extra 0.5" length) in an action that
is only 0.2" longer (long action) or even 0.4" longer (true magnum action).

Bullet weight: 404-gr Shock Hammer easily does +2500 fps from a 24" barrel at COL of 3.380".
Nice trajectory.
For the CEB 400-gr brass FN, 2500 fps is fast enough at less than 3.380" COL.
A shorter solid has more inherent stability in an elephant skull.
Fine and dandy in a 3.4" (standard) action length.

Even with the old factory ammo (lousy bullets) Richard Harland and Ron Thomson slew thousands of elephants in control work with their .458 WinMags, circa 1960 and onward.
Thomson guessed he had made 5000-6000 kills, and backup on many more.
"But what is a few thousand elephant among friends" he said, or something like that.

Really, the saddest thing about the whole deal is how James Watts gets so little credit for starting it all with his .450 Watts Magnum with 2.850" case length, and .450 Watts Short with 2.500" case length, long before anyone else.
Alas, the "Winchester Magnum" moniker was necessary for WRAC to get started on their .458, .338, .264, and .300. Watts signed a release to get WRAC going on it.

Jack Lott used a .450 Watts Magnum chamber reamer in a .458 Winchester Magnum barrel with no set back. He was using 2.800" brass length in a chamber of 2.870" length, meant for 2.850" brass.
Stolen valor.

Hornady, bless their heart, continue to improve their bullets.
The DGX and DGS are their best so far.
We can only hope someday they will get it all alright.

What they do produce in the way of internal and external ballistics needs no improvement.
It is just the terminal ballistic performance of the bullets that is still wanting.

I have been checking MV of the Hornady 500-gr DGS factory load for the .458 WinMag over the last 5 years.
Hornady claims 2140 fps MV in a 24" barrel. They are RIGHT ON.
Ruger No. 1 with factory 24" barrel, 1:14" twist
DGS 500-gr, 5-shot mean = 2145 fps MV at 52*F

Winchester M70 Super Grade (Cabela's) with factory 23-7/8" barrel, 1:14" twist
DGS 500-gr, 5-shot mean = 2135 fps MV at 46*F
DGX 500-gr, 5-shot mean = 2146 fps MV at 46*F

Custom FN M98 with Pac-Nor 24-1/4" barrel, 1:10" twist
DGX 500-gr, 10-shot mean = 2145 fps MV at 86*F
Standard deviation = 7.42 fps
Whenever st.dev. in fps is less than number of shots fired,
that is excellent.

Same lot of ammo for each DGX or DGS above.
Several other rifles tried over the last 5 years.
23" to 25" barrel lengths.
Twist 1:14" for all but the one 1:10" twist.
Groove diameters all within 0.458" to 0.459".
All have SAAMI .458 Winchester Magnum chambers.
Temperatures all within 40*F to 90*F range.

All results very much equivalent to Hornady advertising claims for 500-grain bullet MV.
They got that right.

One ".458 Winchester Special" custom KRAB 98 Mauser rifle I have
has a shorter throat by 0.200" than the SAAMI .458 WinMag chambering.
I got it used, said to be Douglas barrel, has a 1:14" twist, groove is 0.458, barrel length 24-1/4"
from breech face to muzzle crown.

Custom KRAB M98 with Douglas 24-1/4" barrel, 1:14" twist, non-SAAMI short throat:
Hornady factory ammo:
DGX 500-gr, 10-shot mean = 2196 fps MV at 86*F

Pressures and velocities were higher with the shorter throat.
That is how the .458 Lott works.
The SAAMI .458 Lott throat is even shorter than the one on my .458 Winchester Special.

I bought 100 each of the DGS and DGX factory loads about 2018.
The last reported MV above was done in the latter half of 2023.
Shelf life of Hornady .458 WinMag must be pretty good.
At least 5 years with no worries.
Stored at about 70*F and normal central heating and AC home humidity.

The 1957 vintage Winchester ammo was good for 64 years.
Sometime after 1957, the Democrat voters took over the ammo factories.

@Riflecrank

I deeply appreciate your knowledgeable assessment of the .458 Winchester Magnum. I will add a couple of thoughts.

Taking your findings into account, the executives at Winchester must have been doing something right before 1957, which they stopped doing shortly afterwards (probably some misguided attempt at cost cutting measures).

The H.P White Laboratory report where I got the 2087 FPS statistic from, is actually 1961 (See Below).

Powder clumping was definitely a very real phenomenon in at least some of the pre-1970 Winchester factory loaded ammunition for the .458 Winchester Magnum.

I took these photographs, myself. A retired Zimbabwean game ranger friend of mine bought these boxes of ammunition for his .458 Winchester Magnum (a custom piece built on a Springfield Model 1903A3 action) back in the Rhodesian days (from Bulawayo General Supplies). Observe the grotesque degree of propellant clumping.

Since this is a stark contrast to the pristine condition of the vintage 1957 made ammunition, I am thinking that perhaps this is due to the Winchester factory propellant for this caliber being very temperature sensitive ? Zimbabwe is rather hot.


I have corresponded with both Richard Harland and Ron Thompson about rifles and cartridges on more than a few occasions. Both were only using FRESH factory loads (500Gr round nosed steel jacketed Winchester Super Speed FMJ solids) for their elephant culling.

And other prominent elephant cullers (Terry Irwin, Mike LaGrange, Ken Worseley) did document propellant clumping problems with the same type of ammunition if kept in storage in the National Parks armory for more than four years.

Riflecrank said:

Hunter-Habib,
Nice write up, but you forgot to mention the original H. P. White Laboratory tests in 1955.
Julian S. Hatcher, Major General U.S. Army, Retired was Technical Editor for the NRA's AMERICAN RIFLEMAN then. WRAC sent him "the pilot model" .458 Winchester Magnum and ballistics reports: "... no shortcomings in ballistics were noted." This was a recollection recorded in HATCHER'S NOTEBOOK.
His first article on the .458 WinMag in the NRA pub was entitled "For the Biggest Game" and subtitled
"A report on the .458 Winchester Magnum cartridge and rifle," in the August 1956 issue of AR.

The .458 WM exceeded all advertising claims regarding ballistics:
25" barrel
76 degrees F, 59% RH
Bullet: 500-gr WRA FMJ RN
COL: 3.340"
Winchester cases and Winchester 120 primers
Propellant: 71.0 grains of HiVel #2, NOT COMPRESSED
Velocity average for 10 shots: 2160 fps, intstrumental velocity 20 feet from muzzle
Pressure average for 10 shots: 50,410 PSI

Assuming G1 BC was 0.295, corrected to MV = 2174 fps
KE at MV = 5247 ft-lbs

Any of the terrible stuff that happened in the decades after that can be blamed on slobs of one sort or another, mostly at the ammo factories, but end-user abusers as well.

On March 9, 2022 test-fire and dissection of 1957 vintage ammo from WRAC was done by me.
Date code on end flap of the red and yellow Winchester SUPER SPEED box was 91MM8,
indicating Nov. 8, 1957 ammo lot date.
Advertised MV was 2125 fps for the WRAC 500-grain FMJ RN
This .458 WinMag factory load was 64 years and 4 months old when fired.

25" Shilen barrel
51 degrees F
Bullet: 500-gr WRA FMJ RN
COL: 3.331" (brass length = 2.494")
Winchester case, red sealant around primer
Propellant: 67.0 grains of extruded, small grain tubular, charcoal-grey-black color
5-yard chrono for 5 shots: 2072, 2072, 2061, 2065, 2059 Mean = 2066 fps
If G1 BC = 0.295:
MV = 2080 fps

Ammo was stored in homes with central HVAC climate control FOR OVER 64 YEARS.
If that had been HiVel #2 powder, 4 more grains of it might have been nice.
Anyway, not bad stuff, factory loaded before the Democrat voters took over the factory.

Nowadays powders and bullets are so advanced as to allow handloaders near endless options.

This is undeniable:
Load the .458 WinMag to same COL and higher pressure (MAP) as the .458 Lott
is allowed by SAAMI,
and the .458 WinMag will give higher velocity or lower pressure or both, compared to the SAAMI .458 Lott.
It is all in the throat and a bullet long enough to make the span.
Physics does not lie.
Slick up your action and you can work the longer action fast,
don't feel bad about using an H&H-length action for your .458 WinMag.

Here is a funny. The .458 Lott had its brass lengthened by 0.3"
and was meant for primary use in an action only 0.2" longer.
That is a bit cramped.
Don't get me started on using a 3.000" case length (extra 0.5" length) in an action that
is only 0.2" longer (long action) or even 0.4" longer (true magnum action).

Bullet weight: 404-gr Shock Hammer easily does +2500 fps from a 24" barrel at COL of 3.380".
Nice trajectory.
For the CEB 400-gr brass FN, 2500 fps is fast enough at less than 3.380" COL.
A shorter solid has more inherent stability in an elephant skull.
Fine and dandy in a 3.4" (standard) action length.

Even with the old factory ammo (lousy bullets) Richard Harland and Ron Thomson slew thousands of elephants in control work with their .458 WinMags, circa 1960 and onward.
Thomson guessed he had made 5000-6000 kills, and backup on many more.
"But what is a few thousand elephant among friends" he said, or something like that.

Really, the saddest thing about the whole deal is how James Watts gets so little credit for starting it all with his .450 Watts Magnum with 2.850" case length, and .450 Watts Short with 2.500" case length, long before anyone else.
Alas, the "Winchester Magnum" moniker was necessary for WRAC to get started on their .458, .338, .264, and .300. Watts signed a release to get WRAC going on it.

Jack Lott used a .450 Watts Magnum chamber reamer in a .458 Winchester Magnum barrel with no set back. He was using 2.800" brass length in a chamber of 2.870" length, meant for 2.850" brass.
Stolen valor.

Click to expand...

And Ackley magnum which Terry Wieland has been using for quite some years and test loaded a lot of various ammo for .

Hunter-Habib,
Thanks for that. I have read the Aagaard piece and anything else he ever wrote that I could find.
I never looked at the February 1961 AR article he referenced, but I will now.
I was just noting that earlier H. P. White data was available, and much more impressive, way back in 1955. I have posted on it at 24hrcampfire and can get some of that material copied here.
It comes from HATCHER'S NOTEBOOK.

Your associate's caked-powder loads look to be identical to the ones from 1957 that I dissected and test-fired.
But mine were pristine with no clumping, after 64 years of storage in human habitable homes.
I got an MV of 2080 fps in 2023.
H. P. White got an MV of 2086 fps in 1960-1961.
Right on.

Sort of suggests that leakage at the case mouth/crimp could be at fault.
Mere heat and humidity could have done that.
A lacquer sealant in the cannelure of the bullet like around the primer might have prevented that.
Anyway, it was not the notorious ball powder from Winchester turning to goo.
That is a tubular extruded powder with goo on the top surface of the load that was not compressed,
just guessing.

Terry Wieland is a great author.
Scholarly and fun to read.
His research on the origin of the .450 NE via John Rigby was excellent.
Unfortunately, he got sucked up into .458 WinMag denial, almost as badly as Ross Seyfried.

James Watts consulted Ackley, Buhmiller and Barnes in the mid to late 1940s when he was
dreaming up his .450 Watts Magnum with 2.85" straight-taper case. All those other guys (barrel and bullet makers and wildcatters all) subsequently did their own versions with full length case and micro-shoulders just to be different ... after the .450 Watts was shooting in 1949.
I have a .450 Barnes Supreme rifle for 2.85" case from the 1950s cartridge origin. Micro-shoulder.
Barnes even did a micro-shouldered 2.5" case circa 1955.

Even Saint Finn Aagaard may think the long throat on the .458 Winchester Magnum was a goof.
I do not.
Relative to bullet diameter, its throat is shorter than that of the 9.3x62mm Mauser.
Both have wide-based, long-sloped, leade-only throats with no parallel-sided free-bore.
Distance from maximum case length to full-engraving at bore diameter:
9.3x62mm = 1.114"
.458 WM = 1.128"
Those are based on C.I.P. specs for both. The C.I.P. mm are converted to inches.
CIP and SAAMI homologations for the .458 WM are as close as can be with inches to mm conversions,
but CIP allows higher MAP for the .458 WM, same MAP as for their .458 Lott (62, 350 psi/4300 bar)
whereas SAAMI MAP is 60,000 psi for .458 WM and 62,500 psi for the tight-throated .458 Lott.

Both the 9.3x62mm and .458 WinMag perform all out of proportion to their size with proper handloads.

My ideal .458 wildcat chamber would be for a 2.7"-long H&H belted, straight-tapered case
with the same breech-face-to-bore-diameter throat length as in a SAAMI .458 WinMag:
Rechamber the SAAMI .458 WinMag to accept 2.700" brass, with no setback of barrel.
Chamber length of 2.7200" then chamfer down into the residual .458 WinMag throat.
I would call it the .458 Watts Express.
It would be used in either 3.6" or 3.8" magazine boxes, and single-shot rifles.
Even the 3.4"-actioned Ruger M77 Hawkeye can be easily converted to 3.6" length.
Obsoletes the .458 Lott.