Home Forums Hunting & Shooting Express Rifles and Big Bores Only The great 458 Winchester. Everyone should own one at least once

Good to hear that it is on the way !

You're dead on with that ballistics program Sir Ron, i was exactly 10 inches low on the 300 yard steel prior to going on Safari, if it'll open down to 1850 the 404 Hammer is indeed an all game bullet out to 350 long yards, and that's exactly the cut off range i had in mind shooting off sticks for this trip, great stuff!

Yessir, 2460 powder for all bullets in the 458 WM+, 404 Hammers, 450 TSX and 500gr TBSS.

10-4 on the big Pac-Nor, that'll make a dandy on that FN 98.

Ironman,
Glad you have dug out of the post safari pit enough to post again.
You are a legend.
Cue Tennessee Ernie Ford singing "Big Jerry" but with lyrics about safari ...

Here is something funny.
The .458 B&M+ with 16.875" barrel gave 2367 fps MV with the 404-gr Shock Hammer
and a charge of 80.0 grains of AA-2230.
That is in a Pac-Nor 1:10" twist stainless "Super Match."
I SWAG that increasing the length to 24" would add 150 fps.
Velocity would become 2517 fps.
Just 1 fps below your fps for the Safari Load.

The new Pac-Nor will be installed on a .458 WM+ Mauser, 24".
.458 B&M+ is same as .458 WM+, only shorter.
Of course, I will have to compare the AA-2460 max load to the
AA-2230 standard load with the 404-gr Shock Hammer as well as the 400-gr CEB #13 FN.

Western Powders data shows 80.0 grains of AA-2230 as a very safe maximum load
with 400-gr Ol’Barnes Original SSSP loaded to COL of 3.140″
in a 24″-barreled .458 WinMag of 1:14″ twist
Winchester case, F-215 primer,
AA-2230 charge of 80.0 grains
MV = 2452 fps
chamber pressure = 52,746 psi
That is a much shorter bullet than the solid brass FN 400-grainer.
That might be a factor.
Whatever,
I have great results with 80.0 grains of AA-2230.

If you are loading the .458 B&M to 2.990″ COL with the 400-gr #13 FN,
you need to load the .458 WinMag to 3.250″ COL to give equivalence.
Using Norma .458 B&M brass will also require using Norma .458 WinMag brass, etc.

Here is what I got with my .458 B&M+ 16.875″ barrel of 1:10″ twist:



This was fire forming with new brass from R-P .300 RUM as per MIB instructions for the .458 B&M.
Accuracy will be better with proper brass, once-fired, etc., of course.
This was the best of my four loads yesterday:



The fact that I was able to get 3 out of 4 of the standard deviations below 5 fps for a 5-shot group
is promising.
H4198 did do better than AA-2230 in that regard, but this is such a small sample,
no conclusions until tried with post-fire-forming brass.

Simple color-coding of primers, with Sharpie markers,to identify the two fixed powder charges used:



Fired primer appearance, little difference between the two powder charges, with the two different bullets:



No brass extrusion at the ejector slot of boltface, no stickiness.
I consider these good loads.
I expect that 2367 fps with the 404-gr Shock Hammer in a 16.875″ barrel
will become 2517 fps in a 24″ barrel,
whether .458 B&M+ at 3.220″ COL or .458 WM+ at 3.480″ COL.
Pac-Nor 24" .458 WM+ Mauser, yep, I can always cut it shorter if it is too cumbersome, heh-heh.



AA-2230 primers above, H4198 primers below:



Running QuickLOAD for barrel shortening might be one of the things it is good for,
noting no absolutes and it depends, some 18″ rifles are faster than some 22″ rifles, and so on.
Doing that simulation for H4198 and AA-2230 fps in a 24″ barrel and a 16.875″ barrel,
H4198 was 100% burnt in 16.875″, AA-2230 was only 99.44% burnt in 16.875″ barrel.
H4198 lost 147 fps from the chopping.
AA-2230 lost 150 fps from same barrel shortening.

Results agree very well with what has been reported for the shortening of the MIB .458 WinMag from 24″ to 20″.

H4198 load giving 2424 fps with 400-gr bullet in 24″ barrel:
24″ to 22″ loses 17 fps per inch
22″ to 20″ loses 19.5 fps per inch
20″ to 18″ loses 22.5 fps per inch
18″ to 16.875″ loses 25.8 fps per inch.

AA-2230 load giving 2493 fps with 400-gr bullet in 24″ barrel:
24″ to 22″ loses 17.5 fps per inch
22″ to 20″ loses 20 fps per inch
20″ to 18″ loses 22.5 fps per inch
18″ to 16.875″ loses 26.7 fps per inch.

Data posted at MIB:



My comments:
This data compared to the standard (short-throated) .458 B&M with 20″ barrel makes perfect sense.
I lose a little more velocity than expected from the shortening of the barrel only.
Expected loss is 75 fps due to barrel shortening from 20″ to 16.875″.
From 20″ to 18″ = -45 fps, from 18″ to 16.875″ = -30 fps.
45 fps + 30 fps = 75 fps.
Maybe 5 fps is lost to faster twist,
and whatever else may be attributed to longer throat,
when comparing the standard .458 B&M loads fired in the .458 B&M+ Long Throat + Fast Twist.

The long throat allows making up for excess losses when we can add more powder safely.

If one should ever run a SAAMI .458 WinMag reamer into one of his .458 B&M rifles to re-throat it,
I SWAG he would find that AA-2230 gives higher velocity at lower pressure than H4198 does.
Free bore reduces pressure and creates the internal-ballistic effect of greater net case capacity,
not just imaginary.

Shortening from 24″ to 20″ also would produce only about 75 fps loss, with proper handloads.
Therefore, a 24″ barreled .458 B&M+ would be about 150 fps faster than my .458 B&M+ with 16.875″ barrel.
A 2350 fps load in the short barrel becomes a 2500 fps load in the 24″ barrel, with 400-grain bullets.
That is the result many of us get with our SAAMI .458 WM rifles with 24″ barrel, and non-SAAMI handloads.
Shucks, we might be over 60,000 psi by a little, and also might be a tad longer than 3.340″ COL with some loads.
No worse for the wear than with a SAAMI .458 Lott.

The 2350 fps MV 404-gr Shock Hammer gives up only 75 yards to the 2500 fps MV load with same bullet.
At 75 yards the faster load is down to 2347 fps, if G1 BC = 0.419.

The difference is even less with the lower BC 400-gr #13 FN,
less than 30 yards advantage for 150 fps extra velocity, if G1 BC = 0.170.
At 30 yards the 2500 fps MV load is down to 2349 fps.

Yep, critters will hardly be able to tell the difference,
whether you are shooting short barrel or long barrel.

LOL, ironman these days is a quickly fading memory, i may have been a pretty good dog 30 years ago, but holy crap, "Papa Time" is a damn thief!

This is all very good stuff, you keep fooling with those 16 barreled rifles, you'll have to book a hunt in dot head land for a giant Gaur in the magic carpet land thickets ; ]

Sir Jerry,
If you are feeling your age, you just need to rest up a bit more.
Gaur ... now that is one heck of a bovine fantasy.
Mercy bo coops.

I think a 16.9" .458 B&M+ will tone it down at the muzzle to about what your
24" .458 WM+ was doing at 75 yards.
Knocking off about 150 fps at the muzzle might allow a lower impact velocity on long shots
at game.
Gotta handicap the 404-gr Shock Hammer somehow.
Might have to slow it down even more to catch one.

Halloween should be a treat for me when the Pac-Nor barrel arrives,
then we shall get back to .458 WM+.

LOL, i am Sir, decided to give the deer a break this morning, will take the mighty 58 cal round ball Hawken for the final walk this evening as MZ season closes, cant wait to see/read about the new FN 458 WM+..............also, if you get tired of looking at that stone fox Ruger 400 Whelen, i have vault space ; ]

Ok sitting here is an unloved stainless Portuguese M70 338 WM. I want to turn it into a 21” 458. Who is available for the work?

Sir smallfry,

You mean one of these?



I am soon seeing a Master Gunsmith/Mechanical Engineer, no extended pinky finger stuff except on his flintlocks.
I will ask him how it goes.

I have one like yours and do not have the heart to change it.
Perfect little .338 WinMag under 7 pounds bare/empty.
I do have the heart to change this one, soon as the FN M98 is done:

The stock on the MRC is not as good as the one on the All Weather M70 (B&C).
No bedding block, but I will make do.
At least it will be easier to hog out the barrel channel for a fluted N0.6 Sporter (or fatter) if I can find one.
It will be no light weight.
Make it 24" long, of course.

I am taking up Revolutionary War Re-enacting.
Went to a grave marking of my ancestor yesterday, near Berry's Lick, KY.
I wore a tri-corner hat and street clothes.
Even dressed so, they let me march in the color guard and carry one of the 16 battle flags.
Said I could go buckskinner next time.
No $3000 uniform required.
I can use my Beck-School Flintlock Rifle made by the same Builder of my .458 WinMags,
instead of a Brown Bess.
No, I will not be allowed to carry a .458 WinMag, even if I load it with a BP blank.











Reverence was had by all.
Enoch and Margaret had 12 children including an Enoch, Jr., if I am reading that correctly.
That is some reverence right there.
They think Enoch Berry, Senior is buried within a 6-mile radius of the marker.

Sir Ron,
It’s actually a Winchester Ultimate Shadow, which comes in an unfluted barrel. I’ve always like 338s and 340s but like them less today. This rifle is just sitting in one of my safes not doing anything so I figured I’d turn it into a 458. I’d probably just make it a 21 inch 458. I usually make my length of pull 13.25” and put some sort of decent visibility shallow V sights on it. The stock would have to go. I am knee deep in rifle projects but I guess the more being worked on the more likely I’ll get one back sooner then later. Stainless barrel cerakote. Any ideas on who can do 458 work with sights would help. Regarding your reenactment adventure, that is really really cool. It’s fun talking to some of those guys!
S.

Sir smallfry,
Rusty McGee is a year older than me and a year wiser.
He thinks life is too short to work on any guns except those of customers he meets face-to-face.
Lucky me.
Sounds like you have several gunsmiths working for you out west.
Don't suppose you want to visit Rusty in person, do you ?

I had the new barrel for about 3 hours before driving it over to Rusty today, to be installed on the FN Mauser:

1:10" twist is a special purpose twist for the .458 WM.
My plan is for subsonic loads with common low-BC bullets of any weight up to 600 grains, suppressed,
and supersonic loads with some VLD bullets of any weight short enough in length to stabilize.
That is to be determined, 575-grainers for sure, heavier maybe.

1:10" twist is not meant for use with cast bullets.
The standard 1:14" twist is good for that with hardcast sized to .461" using smokeless powders.
Slower twist (1:18" to 1:20") might be better for softer alloys and paper-patched with BP in the .458 WinMag,
and 1:14" is passing good there too.

A chicken in every pot and a .458 WinMag (or a dozen) in every gun safe is what I say.

Sir Ron, question:
How do you think a 1-12 would do with commercial hardcast bullets, such as the Cast Performance ?