quote:

Originally posted by lawndart:
The best bet medium rifle is a 9.3x64. Same ballistics as a .375 Rimless Nitro Express, and it was designed to fit in a standard length action back in 1910!

If you have a popularly priced CZ in 416 Rigby, and have a hankering for a .458, why not just re barrel to the 450 Rigby? Load it to 2,150 - 2,250 fps at a ridiculously low pressure. The larger rifle will help soak up the recoil. Brass is easy to find these days, as well.

Instead of "Long Loading" the .458 Win Mag, and modifying the magazine and bolt, why not just get a used 7mm STW, 375 H&H, etc. - then turn it into the .458 Lott. It also allows doing everything the .458 Win Mag does, at a lower pressure.

I think the best use of the .458 Win Mag is as a bear buster with 400-grain premium bullets. It also would shine in hunting large ungulates at moderate ranges with 350 or 400-grain bullets.

So sayeth Forrest Gump.

What about all those THOUSANDS of elephant that Mike LaGrange has killed with the 458 Winchester. ????
I don't think he would say the 458 was only good as a bear gun.
What about All the other guys like Harry Selby that used the 458 for decades with no complaints.
One thing Ross S. Was very prone to doing was the Cool thing. Lot of guys dished the 458 because Ross did and they wanted to be cool like him.
After his big dish on the 458 . Then his mouthyness about the 500 A-Sq. Both of which I owned and hunted at the time. I didn't read anything he wrote for years. Guess I'm not Cool. That's fine.

Sooooooo who designed the 458WM chamber dimensions?

CTF,

What was the thing with Ross Seyfried and the .500 A-Square?
Ross used to call the "A-Square" stuff "B-Round" as a schtick akin to calling the .458 Win.Mag. a "little bridesmaid."

Ross has aged nicely, just like the .458 Winchester Magnum.

Get a load of this GunsAmerica Digest "blog" he wrote in 2012, at age 61 y.o.:

https://www.gunsamerica.com/bl...ing-the-magnum-myth/

Busting the Magnum Myth! – Choosing YOUR Ideal Hunting Cartridge
by ADMINISTRATOR on OCTOBER 21, 2012
by Ross Seyfried

"Kinetic energy does not matter. Accuracy almost does not matter. The headstamp on the case certainly does not matter. Having more shells in the magazine does not matter. How well you can hit with your rifle is almost all that matters!"


Rip ...

quote:

Originally posted by boom stick:
Sooooooo who designed the 458WM chamber dimensions?

You tell me. Until otherwise known, it was God Himself who designed the .458 Winchester Magnum throat.
Is there any other cartridge throated like it besides the now defunct first iteration of CIP .458 Lott?

Rip ...

Some engineer at Winchester must have done it. Anyone know who were the geeks doing the nerd work back then?

quote:

Originally posted by boom stick:
Some engineer at Winchester must have done it. Anyone know who were the geeks doing the nerd work back then?

I suspect that when their identities are learned, that they will be unavailable for comment, at least on this side of the happy hunting ground.

quote:

Originally posted by RIP:

quote:

Originally posted by boom stick:
Sooooooo who designed the 458WM chamber dimensions?

You tell me. Until otherwise known, it was God Himself who designed the .458 Winchester Magnum throat.
Is there any other cartridge throated like it besides the now defunct first iteration of CIP .458 Lott?

Rip ...

The closest today would be the 378 and 460 Wbys at .75" but of course they are parallel sections.

Although many years ago I saw a couple of reamers at an Australian barrel maker's place for smaller bore Euro calibres, I think but not sure they were some sort of 6.5 mm and they were over an inch.

I freebore was measured or express in "calibres" then the earlier 257 Wbys with .75" freebore would equate to 1.33" in 458 bore size.

Mike,

Page 47.

The old Weatherby throats are not at all similar, since they have parallel-sided free-bore, and more abrupt leade angles.

The .458 Win.Mag. is leade only, starting wide and tapering down at just under 0.5-degree semi-angle on the leade, i.e.,
just under 1-degree of cone angle for the leade.

I know of no other throat like it, still looking for another example.

A paper-patch throat is not quite like it either.
On the 40-90 Sharps Bottle Neck, the throat for paper-patch loading
starts at the end of the case mouth, at a plus tolerance greater than brass neck diameter, with a leade of 5 degrees for semi-angle.
This is like the forcing cone at the end of a shotgun chamber.
That is relatively much wider at the start of the leade, and much more abrupt leade angle, than with the .458 Win.Mag.
The .458 Win.Mag. leade diameter starts at 0.469", about halfway down the slope of the chamber's case mouth chamfer
0*29'30" leade semi-angle.
A .458-caliber bullet diameter starts touching the rifling lands at 0.458" groove diameter, at a distance of 0.6725" from the end of a 2.500" case.
Rifling and bullet are fully engaged at 1.1420" from the case mouth, where the leade has tapered down to 0.450" bore diameter.
The leade vanishes smoothly into full rifling,
just like the .458 Win.Mag. bullet does.
Who would have thought such a throat could work so well?
Mid-1950s Winchester engineers? God only knows!

Rip ...

quote:

Originally posted by RIP:
CTF,

What was the thing with Ross Seyfried and the .500 A-Square?
Ross used to call the "A-Square" stuff "B-Round" as a schtick akin to calling the .458 Win.Mag. a "little bridesmaid."

Ross has aged nicely, just like the .458 Winchester Magnum.

Get a load of this GunsAmerica Digest "blog" he wrote in 2012, at age 61 y.o.:

https://www.gunsamerica.com/bl...ing-the-magnum-myth/

Busting the Magnum Myth! – Choosing YOUR Ideal Hunting Cartridge
by ADMINISTRATOR on OCTOBER 21, 2012
by Ross Seyfried

"Kinetic energy does not matter. Accuracy almost does not matter. The headstamp on the case certainly does not matter. Having more shells in the magazine does not matter. How well you can hit with your rifle is almost all that matters!"


Rip ...

Ya, he and Art Alphin didn't get along.
The only time to my knowledge Ross mentioned them , for some reason he was talking about the 495 A-2 . He called it the B Round. I never figured there was anything the 577 could do that the 500 A-Square couldn't do just as well.

And the thing with the hoopla boys dishing the 458 Winchester. I'm living proof that if a guy has a good strong thumper built. Then goes out and shoots a couple thousand rounds thru it. Over a few years. He's probably going to be able to hit well with it. And it will kill well for him.

Comparing an extended leade differs from freebore as in Weatherby. The Weatherbys that I have seen (Southgate and German) were of dimensions that allowed the initial push of gases to pass by the bullet, thus lowering the pressure while the bullet was accelerated through the bore. PO Ackley did some work on this and determined that the primary result was to waste the powder. If the bore remained sealed so that virtually all the powder stayed behind the bullet, similar velocities were obtained with similar pressures with less powder. So if the 458 was chambered to allow the bullet to be seated farther forward, giving the case volume expanded powder space, while having the throat dimensions such that the bullet sealed the bore very soon after moving forward, it is my expectation that a considerable increase in velocity could be obtained in comparison to either the standard OAL or the extended OAL fired in a Weatherby type freebore.

Hmmmmm..... Interesting.....
So, with the pressure curve on big bores, potentially, you can use multiple powders to try to increase burn rates as the bullet goes down the barrel for increased velocity whilst maintaining reasonable pressure? (Strokes beard). Go from ludicrous speed to plaid in 22"

Hooray! Some discussion of throat!
I am not claiming to understand completely how it works, but the .458 Win.Mag. throat is quite unusual.
So is the performance of the .458 Win.Mag., unusually good, whether ShortCOL (SAAMI 3.340" or less) or LongCOL.
Due to this thread, and my handloading and shooting results, I have come to know this.

I have an old 1947/original-throated .375 Wby.Mag.
That PSFB is about 3/4" long.
Compared to the 2001 version by Weatherby, the old one is slower in MV and less accurate enough to be attributable to the long throat, maybe?
The new throat of 2001 is about half as long in PSFB, 0.373", and the diameter of that PSFB is only 0.0006" greater than bullet diameter.
That's 0.3756" PSFB diameter.
Leade is 1*5'20" semi-angle, by CIP.

That seems to be a good recipe for accuracy and efficient powder burning for good velocity per grain:
Just under one-bullet-caliber length of PSFB, and a tight diameter on that PSFB. Lessens the gas blow-by?
Leade of just a little over 1-degree semi-angle does not seem to hurt anything.



Here is that drawing by Gil Sengel showing the SAAMI .458 Win.Mag. throat, compared to his .458 Winchester Special.



Firing standard .458 Win.Mag. in the "Special" can cause signs of excessive pressure.
A < 53K-psi load in a SAAMI chamber can become a > 65K-psi load in the Gil Sengel chamber, which is designed for 400-grain cast-lead bullets.

That is sort of like firing a top end .458 Win.Mag. LongCOL load in a .458 Lott.
The .458 Lott gets red in the face and wheezes, to paraphrase Ross Seyfried.

Rip ...

Is your lithium level as high as your ad hominem level today?

quote:

A .458-caliber bullet diameter starts touching the rifling lands at 0.458" groove diameter, at a distance of 0.6725" from the end of a 2.500" case.

Just two points, queries:

1. Isn't the 0.6725" functionally equivalent to 0.6725" parallel-sided freebore, possibly different in accuracy?

2. What about the 6.5 Screechmore?

quote:

Originally posted by lawndart:
Is your lithium level as high as your ad hominem level today?

Bro'Dart,

I do not take lithium as a medication nor nutritional supplement, so I do not monitor my blood level of that mineral.
For you to imply that I do is just feeding us more baloney.
We are going to need blood pressure lowering drugs if we eat baloney.
I bet if you are serving up baloney you are eating some of it too.
Think of all that sodium!
Take care of your health.

As for the ad hominem attack, you are the only one guilty of that. You started that when you implied that Forrest Gump was the source of your wisdom/baloney.
Forrest Gump does not deserve that!

Rip ...

quote:

Originally posted by 416Tanzan:

quote:

A .458-caliber bullet diameter starts touching the rifling lands at 0.458" groove diameter, at a distance of 0.6725" from the end of a 2.500" case.

Just two points, queries:

1. Isn't the 0.6725" functionally equivalent to 0.6725" parallel-sided freebore, possibly different in accuracy?

At first blush one might think so. But then one might think the .458 Win.Mag. ought not be as good due to the extra wobble room at the start of the wide-mouth leade.
But somehow, the wide-mouthed, acute-angled, leade-only throat is capable of good accuracy.
Great accuracy when loaded "LongCOL."
The great ability to effectively increase case capacity and keep pressures low is no surprise.
For the leade-only throat, however, the transition from just starting to bear at 0.6725" to fully engraving the bullet at 1.140" from the case mouth,
is a smooth and seamless transition along the gradual and seamless leade of just under 0.5-degree semi-angle, 1-degree cone-angle.

Scaling up the current .375 Wby.Mag. throat to .458-caliber would require a free-bore diameter of only 0.4587"
and about 0.4555" length,
(let's just call that 0.4590" diameter and 0.4560" length, to make the diameter same as on the .458 Lott, and to allow a .459" diameter cast bullet)
then a leade angle of 1*5'20".
That is more than twice as long as the current .458 Lott throat,from case mouth to start of bullet bearing.
That might improve the .458 Lott to the point of being able to compete with the .458 Win.Mag.


2. What about the 6.5 Screechmore?
You're going to have to be more specific on what you are being flippant about here.
Which 6.5mm cartridge are you screeching about?

Rip ...

Creedmoor, long throat. 6.5.

quote:

I bet if you are serving up baloney you are eating some of it too.
Think of all that sodium!
Take care of your health.

I take Tenofovir, and Raltegravir for infection by XMRV, Xenotropic Murine Leukemia Virus Like Virus, one of the retroviridae. No baloney, that is uneatable, awful stuff. No need for antihypertensives. I take a corticosteroid for adrenal failure, but thanks for the concern.

Unfortunately, unable to have a conversation with you on this matter. AMF.

quote:

Originally posted by 416Tanzan:
Creedmoor, long throat. 6.5.

6.5 Creedmoor per SAAMI:
PSFB diameter = 0.2645" for a [0.2644-.0030"] bullet diameter, call it 0.2640" bullet diameter.
So the PSFB is 0.0005" bigger than bullet diameter.
That is proportionally larger than the 0.0006" for the .375 Wby.Mag., though actually 0.0001" tighter.

The PSFB length of the 6.5 Creedmoor is 0.1992" long.
If you include the length of the chamber's casemouth bevel, add 0.0158" to that.
If you include the plus tolerance of the chamber neck beyond the maximum brass length, add only 0.0050" more.
That last bit is remarkable, the chamber proper to end of neck is 1.9250" long, only 0.005" longer than brass maximum of 1.920".
Most cartridges allow 0.010" to 0.020" of chamber minimum length over brass maximum length, for brass stretching and rebounding on firing.
So the 6.5 Creedmoor is tight here, though not exactly headspacing on case mouth.
Better trim that 6.5 Creedmoor brass religiously, whether it needs it or not.

There is another remarkable tightness of the 6.5 Creedmoor, that is the neck diameters of brass neck in chamber neck:
Chamber minimums: neck-2 = 0.2960", neck-1 = 0.2970"
Brass maximums: neck-2 = 0.2950", neck-1 = 0.2950"
Only 0.001" of neck expansion at case mouth (neck-2) to release the bullet.
Only 0.002" of neck expansion at shoulder-neck juncture (neck-1) to release the bullet.
Most cartridges allow 0.003" to 0.004" of neck diameter expansion and rebound on firing.

Leade angle of the 6.5 Creedmoor is 1*30'00" for semi-angle, 3-degree cone-angle, about average as leade angles go, across the cartridge spectrum.

Just figuring the isolated PSFB length as a percentage of caliber diameter for the 6.5 Creedmoor: (0.1992"/0.2640") x 100% = 75.45%

Yep, that is pretty much Weatherbyesque.
And it works very well.
Long PSFB with tight diameter seems to work wonders, as long as the PSFB length is less than one caliber length, and the PSFB diameter is less than 0.001" over bullet diameter.
Only 0.0005" for a .264-caliber bullet,
only 0.0006" for a .375-caliber bullet.

Of course for optimum velocity and accuracy, one must be able to load to an optimum COL in such throats.
Just like with the .458 Win.Mag. throat.
There you go. Staying on topic.

Rip ...

Neat rockclimbing picture:

quote:

Originally posted by lawndart:
... Unfortunately, unable to have a conversation with you on this matter. AMF.

What? No YOYO to go with that AMF?
As MD to MD Bro'Dart, I can only say about your last post: TMI
My flight surgeon to your fighter pilot:
Don't forget the G-suit and straining maneuvers if you are going to pull some tight turns, chasing the .458 Win.Mag. bogey at supersonic.

And if you crack up in midair or on take-off or landing ...



Rip ...

Reminds me of Ross Seyfried having a snit with Phil Shoemaker over the .458 Win.Mag.
Lawndart would be Ross, I would be Phil, for analogy purposes.

Rip ...

quote:

Originally posted by RIP:
Reminds me of Ross Seyfried having a snit with Phil Shoemaker over the .458 Win.Mag.
Lawndart would be Ross, I would be Phil, for analogy purposes.

Rip ...

So Yup. That sounds about correct.

AMF = Adios My Friend. Don't know what "YOYO" means.

Ultimately fatal retroviridae infection is TMI?

Okay, you win. You are correct on every point, and I was wrong on every point.

What does it matter that the 450 Rigby is essentially, or even exactly the same as the 450 Dakota? The Norma brass is cheaper.

I am not skilled or equipped enough to measure the leades or angles of engagement on a chamber, but I do know what I have seen on a few different barrels. The most striking is a 257 Weatherby that was rebarrelled several years ago. The original barrel was German 1960 production, 24" 1-12" twist. It would handle full power factory loads and had velocities in the advertised ranges. It was rebarrelled to 257 Wby, but the chamber was cut to minimum specs and the freebore was virtually eliminated however the contact with rifling was such that the bullets could be seated well out in the neck. The barrel was 28" long and had 1-10" twist. I'm not sure exactly what the dimensions were but the result was that if factory ammunition is fired in it, high pressures develop. The usual suspects are apparent: blown primer, ejector mark, etc. If using factory ammo, it would be a problem rifle. However, I really like it. I can load 120 bullets with a charge less than starting of H870 and get velocities over factory or even what loading manuals show for maximum loads. I have worked loads up to 3600 fps but felt that I was missing something, even though the case could be reloaded five times at the load, so cut back the loads to 3400 fps. I contacted the editor of Handloader magazine about the results and he got quite belligerent about it- claiming that I was running pressures well into unsafe territory and should be glad that I hadn't blown the gun up. He claimed that if I was getting 3300 fps from 28" barrel with a 120 gr bullet, that regardless of barrel configuration I would be at maximum pressure. This was discouraging because it showed a mindset that was fixed and allowed for no information that didn't fit the mould. What I know is this: I can load well below even the starting loads listed in the various manuals and with those loads I get performance levels noted in the manuals using several grains more powder and the brass shows no signs of high pressure (as long as I stay at these "reduced" loads.

So the only conclusion that I can make is that the limiting of blowby, even with allowing the bullet to travel before contacting the rifling will yield significant changes in the performance of the cartridge/bullet. As such, it seems to me that the same rules would apply to the 458 as much as they did to the 257.

quote:

Originally posted by RIP:

quote:

Originally posted by 416Tanzan:
Creedmoor, long throat. 6.5.

6.5 Creedmoor per SAAMI:
PSFB diameter = 0.2645" for a [0.2644-.0030"] bullet diameter, call it 0.2640" bullet diameter.
So the PSFB is 0.0005" bigger than bullet diameter.
That is proportionally larger than the 0.0006" for the .375 Wby.Mag., though actually 0.0001" tighter.

The PSFB length of the 6.5 Creedmoor is 0.1992" long.
If you include the length of the chamber's casemouth bevel, add 0.0158" to that.
If you include the plus tolerance of the chamber neck beyond the maximum brass length, add only 0.0050" more.
That last bit is remarkable, the chamber proper to end of neck is 1.9250" long, only 0.005" longer than brass maximum of 1.920".
Most cartridges allow 0.010" to 0.020" of chamber minimum length over brass maximum length, for brass stretching and rebounding on firing.
So the 6.5 Creedmoor is tight here, though not exactly headspacing on case mouth.
Better trim that 6.5 Creedmoor brass religiously, whether it needs it or not.

There is another remarkable tightness of the 6.5 Creedmoor, that is the neck diameters of brass neck in chamber neck:
Chamber minimums: neck-2 = 0.2960", neck-1 = 0.2970"
Brass maximums: neck-2 = 0.2950", neck-1 = 0.2950"
Only 0.001" of neck expansion at case mouth (neck-2) to release the bullet.
Only 0.002" of neck expansion at shoulder-neck juncture (neck-1) to release the bullet.
Most cartridges allow 0.003" to 0.004" of neck diameter expansion and rebound on firing.

Leade angle of the 6.5 Creedmoor is 1*30'00" for semi-angle, 3-degree cone-angle, about average as leade angles go, across the cartridge spectrum.

Just figuring the isolated PSFB length as a percentage of caliber diameter for the 6.5 Creedmoor: (0.1992"/0.2640") x 100% = 75.45%

Yep, that is pretty much Weatherbyesque.
And it works very well.
Long PSFB with tight diameter seems to work wonders, as long as the PSFB length is less than one caliber length, and the PSFB diameter is less than 0.001" over bullet diameter.
Only 0.0005" for a .264-caliber bullet,
only 0.0006" for a .375-caliber bullet.

Of course for optimum velocity and accuracy, one must be able to load to an optimum COL in such throats.
Just like with the .458 Win.Mag. throat.
There you go. Staying on topic.

Rip ...

Thanks.

You are a gentleman and scholar.

quote:

Originally posted by lawndart:

quote:

I bet if you are serving up baloney you are eating some of it too.
Think of all that sodium!
Take care of your health.

I take Tenofovir, and Raltegravir for infection by XMRV, Xenotropic Murine Leukemia Virus Like Virus, one of the retroviridae. No baloney, that is uneatable, awful stuff. No need for antihypertensives. I take a corticosteroid for adrenal failure, but thanks for the concern.

Unfortunately, unable to have a conversation with you on this matter. AMF.

Nice to see a photo of a PROPER fighter!


From a former Hornet driver! Check Six MoFo!!

Ray B; that's a good post . sounds like you have an interesting 257. 5 reloads on brass is pretty good !

With a larger "effective" case capacity due to the unique throat of the 458 Win Mag, could one utilize slower powders than should be optimal in this almost straight-walled case given a shorter more conventional freebore?

quote:

Originally posted by lawndart:
AMF = Adios My Friend. Don't know what "YOYO" means.
Yes, but "AMF" can also mean "Adios Mo' F-er" so it is really not a nice thing to type or say.
"YOYO" is "You're On Your Own."
Like when the chief resident in surgery steps into the elevator and as the door closes he calls out to the intern in the ward "AMF YOYO."

Ultimately fatal retroviridae infection is TMI?

Yes, TMI. I am retired from medicine, and I get PTSD symptoms if a bunch of medical jargon is trotted before me.
Well, that is my excuse story, and I am sticking to it.

Okay, you win. You are correct on every point, and I was wrong on every point.

Oh, don't be so silly. Everything is relative. Relative to this thread, you were more wrong than right.

What does it matter that the 450 Rigby is essentially, or even exactly the same as the 450 Dakota? The Norma brass is cheaper.

.450 Dakota: 1986 by Dakota Arms, Sturgis, South Dakota. Don Allen design, did Art Alphin collaborate?
Base diameter = 0.5820", exactly what a 460 Wby.Mag. measures above the belt. Suggests how brass was made for it before BELL .416 Rigby, eh?
Rim diameter = 0.5820"

.450 Rigby Rimless Magnum: 1994 by Paul Roberts of John Rigby & Co., the first new cartridge for that company since 1911's .416 Rigby.
Base diameter = 0.5890"
Rim diameter = 0.5902"

Pierre van der Walt says this about the "relative case capacity" for the two cartridges:

.450 Dakota: 137.0 grains 0f water
.450 RigbyRM: 133.0 grains of water

I bet if we investigated the throating of those two, we could add some replies to this thread.

OK, so the only advantage the .450 Rigby has is brass availability. Just neck up and fire-form .416 Rigby, or get proper headstamp.

.450 Dakota brass is not unobtainable. I have my stockpile, and would not consider trying to size the base of .416 Rigby down by .007".
But I could turn the belts off of 460 Wby.Mag. brass, and I have lots of that.
The rim on the 460 Wby.Mag. (0.5790") is only .003" lesser diameter than the 0.5820" of the .450 Dakota,
But that is no problem, not critical. Suggests again how Don Allen came up with it.
I am secure in liking my .450 Dakota, better than I could ever like a me-too late-comer like the .450 Rigby.

The .450 Dakota is a technically superior cartridge,
and it is a proud American.
Hey! That makes it just like the .458 Winchester Magnum.

Rip ...

Todd,

Did you have to copy all that medical jargon?
I was prostrated by a flashback when I read that for the second time.
PTSD.

Rip ...

quote:

From a former Hornet driver! Check Six MoFo!!

I enjoyed DACT with Hornet aviators from 1983 through 1996 at various Flag exercises, scheduled deployments from Europe to Hawaii, and especially in California. Even ran into some hornet drivers at Constant Peg. What was your favorite squadron, and best carrier to operate off of. I almost took a dual rated Aviator/Physician slot in Hornets in the early 1990s, but ended up in Alaska instead. You should have someone sponsor you onto the Old Fighter Pilots site (restricted to front seaters of fighter/attack aircraft with their own, private, face book account (no wives allowed to view).

quote:

Relative to this thread, you were more wrong than right.

What single point was I right on?

Hornets?? Bah HumBug!! I know the performance numbers, but there is nothing like being on the ground, outnumbered by a bunch of "them" and seeing the Earth erupt where "they" once were, followed by the concussion of the ordnance followed immediately by the sound of the F4 Phantom that had just reduced the ratio of them to us.

quote:

Originally posted by Ray B:
... The most striking is a 257 Weatherby that was rebarrelled several years ago. The original barrel was German 1960 production, 24" 1-12" twist. It would handle full power factory loads and had velocities in the advertised ranges.

Must have had the 0.378"-long PSFB, unchanged since 1945 origin?
SAAMI standard is 0.378" of free-bore including the case mouth bevel, but only 0.3627" length for the isolated length of PSFB.
A Clymer reamer drawing from 2005 shows 0.3780" PSFB and the free-bore diameter is 0.2575", leade semi-angle 1 degree.
The 2015 SAAMI PSFB diameter is 0.2574", and 0*57'0" semi-angle for leade.

It was rebarrelled to 257 Wby, but the chamber was cut to minimum specs and the freebore was virtually eliminated however the contact with rifling was such that the bullets could be seated well out in the neck. The barrel was 28" long and had 1-10" twist.

Going from 24" to 28" would have added velocity significantly with that sort of cartridge, if other factors were unchanged.
Twist rate change should have been negilgible on velocity and pressure effects.
Barrel differences in goove and bore diameters, and maybe even the finish on the lands would have greater effects than the small change in twist.

I'm not sure exactly what the dimensions were but the result was that if factory ammunition is fired in it, high pressures develop.
The usual suspects are apparent: blown primer, ejector mark, etc. If using factory ammo, it would be a problem rifle. However, I really like it. I can load 120 bullets with a charge less than starting of H870 and get velocities over factory or even what loading manuals show for maximum loads. I have worked loads up to 3600 fps but felt that I was missing something, even though the case could be reloaded five times at the load, so cut back the loads to 3400 fps.
I contacted the editor of Handloader magazine about the results and he got quite belligerent about it- claiming that I was running pressures well into unsafe territory and should be glad that I hadn't blown the gun up. He claimed that if I was getting 3300 fps from 28" barrel with a 120 gr bullet, that regardless of barrel configuration I would be at maximum pressure.

Hodgdon Annual Manual of 2018:
.257 Wby.Mag.
26" barrel, 1:10" twist
120-grain Swift SP
IMR-7828 69.0 grains >>> 3325 fps <<< 53,000 CUP
SAAMI MAP is 62,500 PSI

This was discouraging because it showed a mindset that was fixed and allowed for no information that didn't fit the mould. What I know is this: I can load well below even the starting loads listed in the various manuals and with those loads I get performance levels noted in the manuals using several grains more powder and the brass shows no signs of high pressure (as long as I stay at these "reduced" loads.

I reckon 3400 fps with 120-grainers in your 28"-barreled .257 Wby.Mag. is a good plan.

So the only conclusion that I can make is that the limiting of blowby, even with allowing the bullet to travel before contacting the rifling will yield significant changes in the performance of the cartridge/bullet. As such, it seems to me that the same rules would apply to the 458 as much as they did to the 257.

Well that sure points up how a longer throat can allow one to burn more powder, but it is still apples to oranges for the PSFB-style throat versus the leade-only throat.

I have a .257 Weatherby made on a tang-safety, pushfeed Ruger M77, with 25" Shilen barrel, 1:10" twist IIRC, standard long throat.
All I ever used in it was factory ammo, performed as expected. Back then it was the ultimate flat-shooting big game rifle.
I never handloaded for it, but must give it a whirl someday.

When the .375 RUM first came out, I had a gunsmith who is now an MD to put together one for me on a CZ 550 Magnum action.
It had only 23" of medium-heavy barrel length, and I shot it alongside a Remington M700 factory rifle with 26" of lighter contour barrel.
Unbeknownst to me, my custom .375 RUM had been done with a very short-throated reamer, shorter than the factory .375 RUM throat.
I used Remington factory ammo.
The custom 23" rifle blew primers and got higher velocity than the 26" factory rifle that did not blow primers.
Gas blow-by is not a big concern with the .458 Win.Mag, IMHO.
The bore is big enough to handle a little gas without being damaged before the bullet plugs it.
But throat length effects are profound in many ways, aye.

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quote:

Originally posted by bcelliott:
With a larger "effective" case capacity due to the unique throat of the 458 Win Mag, could one utilize slower powders than should be optimal in this almost straight-walled case given a shorter more conventional freebore?

It ain't that much effectively bigger.
It is just effectively bigger than the .458 Lott.

Just use .458 Lott STARTING loads as .458 Win.Mag. LongCOL STARTING loads, and beat a .458 Lott.

Or use standard SAAMI .458 Win.Mag. MAXIMUM loads (which are limited only by short COL, bullet length, and powder compression issues)
as STARTING loads for the .458 Win.Mag. LongCOL.

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quote:

Originally posted by lawndart:

quote:

Relative to this thread, you were more wrong than right.

What single point was I right on?

You were arguably right about .450 Rigby brass being easier to come by than .450 Dakota brass, nowadays.
But that is all, only a minor logistical issue,
and will be a personal choice as to what is the most expensive or troublesome to the individual.
The wise rifleman still prefers a .450 Dakota.
He has a stash of properly headstamped brass,
and makes his plinking ammo from all the old, once-fired 460 Weatherby brass he has lying around from his many past birthday celebrations.
You know, when he takes the 460 Wby.Mag. to the range once a year on his birthday to fire off a few rounds, to see if he still has the right stuff.

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quote:

Originally posted by lawndart:

quote:

From a former Hornet driver! Check Six MoFo!!

I enjoyed DACT with Hornet aviators from 1983 through 1996 at various Flag exercises, scheduled deployments from Europe to Hawaii, and especially in California. Even ran into some hornet drivers at Constant Peg. What was your favorite squadron, and best carrier to operate off of. I almost took a dual rated Aviator/Physician slot in Hornets in the early 1990s, but ended up in Alaska instead. You should have someone sponsor you onto the Old Fighter Pilots site (restricted to front seaters of fighter/attack aircraft with their own, private, face book account (no wives allowed to view).

Howdy LD!

I was actually one of the early members on the Old Fighter Pilot's Facebook page! I deleted my FB account a few months back. Just got tired of the BS on FB, kind of like I get tired of the BS here on AR from time to time!



But yea, 18's vs 16's. Always a GREAT fight, eh! First guy to make a mistake goes down!! Have to be on your best game unlike any of the other guys, at least once you're in phone booth fighting space!



I got Cats/Traps on 3 carriers but only one fleet assignment before getting out and heading to the airlines. That was on the Roosevelt (CVN-71) during Desert Storm in StrikeFighterSquadron (VFA) 87. Good times back then ... a lifetime ago it seems.


Ray B ... Phantoms Phore Ever!!!

Almost to page 48.
I can quote Ross Seyfried until the cows come home.
Page #458 will be here soon enough.
Too soon for some folks.

quote:

But yea, 18's vs 16's. Always a GREAT fight, eh! First guy to make a mistake goes down!! Have to be on your best game unlike any of the other guys, at least once you're in phone booth fighting space!



I got Cats/Traps on 3 carriers but only one fleet assignment before getting out and heading to the airlines. That was on the Roosevelt (CVN-71) during Desert Storm in StrikeFighterSquadron (VFA) 87. Good times back then ... a lifetime ago it seems.


Ray B ... Phantoms Phore Ever!!!

Learning my trade in the F-4 made all that follow so much better. Viper babies did not know how to fight with rudders at high AOA. They eventually learned. I still remember getting into a rolling scissors with a Hornet out west. We never got below 300, 'er 2,500 feet, and never above 3,500 feet. After eight passes we just escaped in opposite directions. No room for error, yes! The Hornet was a real challenge in the phone booth, unlike the Eagle.

OFP is the only reason I am on FB at all. If you're ever in Idaho, dinner is on me.

Charlie Noak

Time out for a jackalope:



When I was 17, President Richard Nixon nominated me for the USAF Academy.
With my spectacles, my vision was as good as Chuck Yeager or Ted Williams.
Their quota for the four-eyed was full.
After flight training, if eyes go worse than 20/20, the old farts put on their spectacles and hop into the cockpit.
Nuts!

So Bro'Dart and Todd,

Did you ever know of any fighter pilots that flew with spectacles? I never saw any, some older Huey and Hercules pilots, yes.
How about those fighter pilots?
Were any of them four-eyed?

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